Ventilation system

ABSTRACT

A respiration device ( 1 ) supports cardio-pulmonary resuscitation (CPR) and a method for operating a respiration device ( 1 ) supports cardio-pulmonary resuscitation (CPR). The respiration device ( 1 ) has a control and regulation unit ( 7 ) in order to actuate an expiratory metering unit ( 3 ), and an inspiratory metering unit ( 2 ) such that, in a first phase, a current value of pressure is increased relative to a first pre-defined value ( 16 ) and such that, in a second phase, the current value of the pressure is reduced relative to the first pre-defined value ( 16 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application under 37 CFR 1.53(b) ofpending prior application Ser. No. 14/652,920 filed Jun. 17, 2015, whichclaims the benefit (35 U.S.C. §120 and 365(c)) of InternationalApplication PCT/EP2013/077035 filed Dec. 18, 2013 and claims the benefitof priority under 35 U.S.C. § 119 of German Patent Application 10 2012024 672.2 filed Dec. 18, 2012, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to a ventilation system (also known as arespiration system) with a gas supply device with a tube arrangement,wherein the tube arrangement has a patient port for connection to apatient in order to send gas from the gas supply device to the patientand to remove gas exhaled by the patient, with a gas flow-controllingdevice from the gas supply device to the patient port and forcontrolling the gas flow away from the patient port, with a sensor unit,which is arranged in the tube arrangement and is set up to detectparameters of the gas supplied to the patient and exhaled by thepatient, and with a control and regulation unit for controlling the gassupply device and the gas flow-controlling device, which is connectedwith the gas supply device, the gas flow-controlling device and thesensor unit.

BACKGROUND OF THE INVENTION

A situation in which it is necessary both to ventilate a patient and toperform a cardiopulmonary resuscitation on that patient frequentlyoccurs in case of the mechanical ventilation of patients, especially inemergency use. The patient is mechanically ventilated, as a rule, via amask or an endotracheal tube by means of an emergency ventilator.

On the one hand, emergency ventilators, which make the mechanicalventilation of the patient possible in emergency situations, are knownfrom the state of the art. Emergency ventilators are characterized inthat they can be used as mobile, portable, autarchic devicesindependently from external electric power and breathing gas supply.Emergency ventilators are shown in DE 4007361 A1 as well as DE 20315975U1. In addition, portable and mobile ventilators are known from thefield of assisting therapy for both clinical and home use. Thus, DE8418594 U1 describes a device for acute intervention in asthma,cardiovascular accidents, myocardial infarctions, circulatory symptomsand even for long-term use in the therapy of chronic bronchitis. On theother hand, devices are known that assist the user in performingcardiopulmonary resuscitation (CPR). Cardiopulmonary resuscitation (CPR)is performed by a helping and rescuing person, optionally withassistance of a second person, manually as an alternation betweenpressure massage of the chest and rescue breathing by means ofmouth-to-mouth or mouth-to-nose resuscitation. The alternation betweenpressure massage and rescue breathing is usually performed at acontinuous rhythm of 30 pressure massages of the chest alternating with2 rescue breaths or at a continuous rhythm of 15 chest massagesalternating with 2 rescue breaths until the patient's cardiovascularsystem resumes functioning on its own, i.e., there is a regularheartbeat again. The rescue breathing is subsequently continued untilthe patient becomes able to breathe on his own again. We also speak of a30-to-2 cardiopulmonary resuscitation (CPR), but it has additionalvariations as well. One person performs alternatingly the chest massagesand the rescue breathing in case of the so-called one-rescuer method,and one person performs the chest massage and the second person therescue breathing in case of the so-called two-rescuer method. Devices,which assist the 30-to-2 rhythm by optical and/or acoustic signalgeneration and enable the person/persons to concentrate essentially onthe performance of the cardiopulmonary resuscitation (CPR) and thepatient's status, are available as an aid for the first and/or secondperson.

Devices for assisting the helping and rescuing persons are described inUS 2006 111 749 A1.

Furthermore, training devices and simulators for clinical staff fortraining in the performance of pressure massage of the chest withcorrect pressure alternating rhythmically properly with the rescuebreathing with correct ventilation (quantity of air) are known. Suchtraining devices and simulators are described in US 2004 058 305 A1.

U.S. Pat. No. 8,151,790 described as another state of the art a valvethat may be arranged between a ventilator and a patient for simultaneoususe with cardiac massage in order to change the filling of the lungsover time and the pressure in the lungs, as well as the changes inpressure over time in relation to the time frame of inspiration andexpiration phases, which time grid is supplied by the ventilator.

A cardiopulmonary device for resuscitating (CPR) a patient forperforming cardiac massage and with a device for controlling aventilator is known from EP0029352 B 1. The ventilator is actuated heresuch that outflow of air from the patient's lungs is prevented from timeto time synchronously with the cardiac massage during the transportationof blood from the heart into the patient's body (systole).

U.S. Pat. No. 6,155,257 shows a ventilator as well as a method foroperating the ventilator in conjunction with a cardiopulmonaryresuscitation (CPR), wherein the ventilation is adapted to thecardiopulmonary resuscitation (CPR). A valve is provided, which isarranged in the gas flow to the patient, in order to delay or preventthe inflow of gas into the patient's lungs until the pressure in thepatient's chest cavity has fallen below a predetermined vacuum valuerelative to the ambient pressure.

When an emergency ventilator is used, the cardiopulmonary resuscitation(CPR) is performed in a usual emergency situation by a helpersimultaneously with and superimposed to, but essentially independentlyfrom the ventilation. Cardiac massage (CM) is necessary for maintainingthe patient's circulatory function in order to supply essentially thebrain and other body parts with oxygen by maintaining the blood flowfrom the heart over the lungs into the body parts to avoid damage,especially permanent damage developing in the brain relativelyimmediately in case of oxygen deficiency and thus to ensure the supplyof oxygen from the lungs into the cells of the body parts and a removalof carbon dioxide from the cells of the body. It is thereforeadditionally necessary to supply fresh breathing air with a sufficientpercentage of oxygen to the lungs. This supply may be achieved by manualrescue breathing by a helper with an oxygen concentration of about 16%or by the use of an emergency ventilator with variable and adjustableoxygen supply.

It is advantageous for the use of cardiac massage that the heart cannotyield when pressing in the chest. Since the possibilities for yieldingare limited relatively constantly essentially by the anatomy of the ribsand the organs directly below the chest cavity (stomach, spleen, liver),the expansion space that remains available for yielding is thethree-dimensional area of the lungs. Whenever the lungs are emptiedcompletely to the extent that only the so-called functional residualcapacity (FRC) is filled with air, i.e., at the end of each expirationphase, the so-called expiration phase, the three-dimensional area inwhich the heart can yield has its maximum. If the heart in the chestcavity has a possibility of expanding, the effect of the cardiac massageis weaker, despite the application of massive force on the patient'schest by the helper, relative to the delivery of blood from the heart tothe body parts, especially the brain, which is brought about by thecardiac massage, than when this space is not available for yielding. Asa consequence of this, there is a less effective exchange between theoxygen present in the blood and carbon dioxide and, associated herewith,there is especially a less adequate oxygen supply for the brain, whichleads to an increase in the probability of permanent damage for thepatient. It is therefore advantageous when performing cardiac massagethat the lungs be filled extensively or not emptied substantially duringthe phase of compression of the cardiac massage, so that thethree-dimension area in which the heart can yield is minimized and thusthe effect of the cardiac massage and hence indirectly also the pressureof the blood flowing into the body (systolic blood pressure) areincreased and the exchange between the oxygen present in the blood andcarbon dioxide is improved.

Furthermore, it is advantageous when performing the cardiac massage thatthe patient's lungs are emptied nearly completely, except for the volumeof the functional residual capacity, during the phase of decompressionof the cardiac massage, and even a slight vacuum is ideally broughtabout in the lungs in relation to the ambient pressure in order toassist the backflow of the blood to the heart. Thus assistance arisesfrom the fact that sufficient space is available for the heart and thevenous blood vessels leading to the heart in the chest cavity of thepatient for the backflow of blood, and the nearly emptied lungs will notfill out this space. An additional aspect is that the blood pressure ofthe blood flowing back (diastolic blood pressure) is not affected by theventilation pressure prevailing in the lungs and is possibly increasedthereby. As a consequence of the assistance of the backflow of the bloodto the heart, an improvement in the blood perfusion and the exchange ofblood in the heart as a whole will thus lead indirectly to animprovement of the exchange of oxygen and carbon dioxide in the bloodcirculation. As a consequence of the improved exchange of oxygen andcarbon dioxide in the blood, the risk of permanent damage to thepatient, especially to the patient's brain, will decrease. If aconventional cardiopulmonary resuscitation (CPR) is performed accordingto the one-rescuer method, the 30-to-2 rhythm is used with the use ofventilation through a face mask. Cardiac massage and ventilation are notperformed simultaneously here. As soon as an additional rescuer,especially an emergency physician, becomes available in an emergencysituation, the mask is replaced with an endotracheal tube, and theendotracheal tube is connected to an emergency ventilator by means of atube connection. Such an endotracheal tube will be called “tube” forshort in the course of the further description of the presentapplication. This has the advantage that the access to the lungs remainsfree, because it is ensured by the tube that no material aspirated bythe patient from the gastrointestinal region can be transported into thepatient's lungs during the performance of the rescue breathing. As soonas the access to the patient's airways is ensured, continuousventilation is performed by means of the ventilator. At the same time,the cardiac massage is continued continuously by a rescuer or a suitabledevice.

A suitable device for applying the mechanical cardiac massage to thechest of a patient is described, for example, in EP0509773 B1.

The continuous compressions of the chest cavity as the effect of thecardiac massage affect, contrary to the cardiopulmonary resuscitation(CPR) with an alternation between cardiac massage and ventilation, forexample according to the 30 (cardiac massages) to 2 (ventilation cycles)rhythm, the 15-to-2 rhythm or the 10-to-2 rhythm, both the manner offilling of the lungs by the ventilator and the resulting pressurechanges in the lungs.

Thus, there is a superimposition of the pressure changes of expirationand inspiration, caused by the ventilation and the selected form ofventilation (ventilation mode), and the compressions caused by thecardiac massage in the curve describing the changes in the measuredventilation pressure during the operation of the ventilator. Threegeneral basic ventilation forms, variants of pressure-regulatedventilation forms, variants of volume-regulated ventilation forms,variants of flow-regulated ventilation forms, as well as combinationsthereof, for example, a pressure-regulated ventilation form with volumeguarantee and maximum flow limitation, are provided by a ventilatoraccording to the state of the art for ventilating a patient. Thissuperimposition due to and of the compressions of the cardiac massagerepresents an additional marginal condition and an interference variablefor the regulation of the ventilation pressure, especially in thepressure-regulated forms of ventilation.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a ventilation systemfor assisting cardiopulmonary resuscitation (CPR) as well as a suitablemethod for assisting cardiopulmonary resuscitation (CPR).

This object is accomplished by a ventilation system with a gas supplydevice, with a tube arrangement, wherein the tube arrangement has apatient port for connection to a patient in order to send gas from thegas supply device to the patient and to remove gas exhaled by thepatient, with gas flow-controlling device from the gas supply device tothe patient port and for controlling the gas flow away from the patientport, with a sensor unit, which is arranged in the tube arrangement andis set up to detect parameters of the gas supplied to the patient andexhaled by the patient, with a control and regulation unit forcontrolling the gas supply device and the gas flow-controlling device,which is connected to the gas supply device, to the gas flow-controllingdevice and to the sensor unit, wherein the control and regulation unitis designed such that in a first mode of operation, the gasflow-controlling device is actuated during an expiration phase such thatthe pressure of the gas exhaled by the patient at the patient port isdescribed by a first curve (pressure time relationship), and the gasflow-controlling device is actuated during an inspiration phase suchthat the pressure of the gas supplied to the patient at the patient portis described by a second curve, wherein the expiration phase and theinspiration phase follow one another continuously alternatingly, whereinthe control and regulation unit is designed to have a second mode ofoperation, wherein the control and regulation unit is designed such thatin the second mode of operation, the gas flow-controlling device isactuated during the expiration phase such that the pressure of the gasexhaled by the patient at the patient port is described by a third curvethat is increased compared to the first curve at least during onesection of the expiration phase, and the gas flow-controlling device isactuated during an inspiration phase such that the pressure of the gassupplied to the patient at the patient port is described by a fourthcurve, which is reduced compared to the second curve, at least duringone section of the inspiration phase, and a device is provided forswitching over the control and regulation unit between the first mode ofoperation and the second mode of operation.

The ventilation system according to the present invention thus canoperate in a first mode of operation, in which the changes in thepressure of the breathing gas with which the patient is supplied aredescribed by a first and second curve during the inspiration phase andthe expiration phase, respectively. This means that the pressuredescribed by the first curve and the second curve consecutively assumeover time a series of values, which are stored in the control andregulation unit. These curves are provided for a normal ventilation of apatient and may vary depending on the patient.

In addition, the ventilation system according to the present inventionand the ventilation system control and regulation unit are designed(configured), however, such that a second mode of operation is provided,in which curves differing from the first curve and the second curve areselected during both the inspiration phase and the expiration phase, atleast in some sections, for the pressure that the breathing gas beingsupplied to the patient has during these phases.

These second and third curves are selected such that the curve of thepressure, i.e., the third curve, is increased during the expirationphase compared to the curve in the first mode of operation. This meansthat the values obtained for the pressure of the breathing gas will thenbe higher during the expiration phase of the second mode of operationthan those that are obtained at corresponding times in the first mode ofoperation.

If the second mode of operation is selected when a cardiopulmonaryresuscitation is being performed on the patient, the pressure in thelungs is increased during the expiration phase relative to the normalventilation in the first mode of operation. The consequence of this isthat the heart can yield less markedly into the area of the lungs duringthe compression of the chest associated with the cardiopulmonaryresuscitation and is thus compressed more strongly, so that more bloodis pressed out of the area of the heart.

Moreover, the pressure curve during the inspiration phase, i.e., thefourth curve by definition, is selected to be such in the second mode ofoperation that it assumes lower values at least in some sectionscompared to the curve in the first mode of operation, i.e., the secondcurve. This also means here that the values obtained for the pressure ofthe breathing gas at the patient port are lower, at least in somesections, than those obtained at corresponding times during theinspiration phase in the first mode of operation. This fourth curve isconsequently lowered relative to the second curve. If the second mode ofoperation is activated together with a cardiopulmonary resuscitation,this will lead to an initially greater contraction of the patient'slungs and to the heart being able to expand to a greater extent, so thatmore blood will flow back into the blood vessels of the heart than thiswould be the case if the patient were ventilated according to the firstmode of operation.

It is consequently achieved due to the provision of two modes ofoperation in the ventilation system according to the present inventionthat the operation of this ventilation system can be adapted to whetherthe patient is undergoing a cardiopulmonary resuscitation or not, andthe effect of the resuscitation measure is optimized hereby.

The control and regulation unit is preferably designed to actuate thegas flow-controlling device such that the expiration phase and theinspiration phase have two consecutive partial phases in the second modeof operation, and the pressure of the gas being exhaled by the patientat the patient port is described by the third curve during the firstpartial phase of the expiration phase, the pressure of the gas beingexhaled by the patient at the patient port is described by a curvecorresponding to the first curve during the second partial phase of theexpiration phase, the pressure of the gas being supplied to the patientat the patient port is described by the fourth curve during the firstpartial phase of the inspiration phase, and the pressure of the gasbeing supplied to the patient at the patient port is described by acurve corresponding to the second curve during the second partial phaseof the inspiration phase.

The ventilation of the patient is changed during the application of acardiopulmonary resuscitation in this preferred embodiment of theventilation system such that the pressure of the breathing gas at thepatient port during the inspiration phase is increased in the secondmode of operation that is now triggered only at the start, namely, inthe first partial phase, while it is described in the further part ofthe inspiration phase, namely, the second partial phase, by the samecurve as during normal operation, i.e., in the first mode of operation.The expiration phase is likewise divided analogously into two partialphases in this preferred embodiment, but a reduction of the pressurerelative to the first mode of operation takes place here only in thechronologically first partial phase, while the pressure curve in thesecond partial phase corresponds to that also seen during the normalventilation, i.e., in the first mode of operation.

Due to the fact that changes occur in the pressure curve only at thestart of the inspiration phase and expiration phase, the desired effectof increased blood circulation at the heart is achieved, on the onehand, but the patient's breathing is not made difficult over the entireexpiration phase and inspiration phase.

To achieve the pressure increase at the start of the expiration phase aswell as the reduction at the start of the inspiration phase, it ispreferably possible for the control and regulation unit to be designedto actuate the gas flow-controlling device such during the expirationphase, for the third pressure curve to be obtained by increasing adesired pressure value. In addition, the control and regulation unit maybe designed to actuate the gas flow-controlling device during theinspiration phase such that the fourth pressure curve is obtained byreducing a desired pressure value.

As an alternative to this, the tube arrangement may have a breathing gasoutlet line, which leads away from the patient port and can be openedand closed relative to the patient port by an expiration valve, theexpiration valve being connected to the control and regulation unit andthe control and regulation unit being designed to actuate the expirationvalve during the expiration phase such that it is opened with a timedelay relative to the start of the expiration phase. In the same manner,the tube arrangement may have a breathing gas supply line, which leadsfrom the gas supply device to the patient port and can be opened andclosed relative to the patient port by an inspiration valve, theinspiration valve being connected to the control and regulation unit,the control and regulation unit being designed to actuate theinspiration valve during the inspiration phase such that it is openedwith a time delay relative to the start of the inspiration phase.

The pressure increase at the start of the expiration phase and thereduction at the start of the inspiration phase are achieved in arelatively simple manner in this alternative by the corresponding valvesin the tube arrangement being opened with a delay, so that the patient'sbreathing and the absence of outflow or inflow of gas leads to thepressure change relative to the first and second curves.

A switch over device, with which the user can switch the control andregulation unit over between the first mode of operation and the secondmode of operation, is preferably provided at the ventilation system. Theswitch over device may also be embodied in the form of software, viawhich the system is controlled and which will then provide a function bywhich a user can switch over between the modes of operation on a userinterface.

As an alternative or in addition, the control and regulation unit may bedesigned to determine from the parameters detected by the sensor unitwhether a cardiopulmonary resuscitation is being performed on a patientconnected to the patient port, and to select the second mode ofoperation when parameters corresponding to a cardiopulmonaryresuscitation are present. This will make it possible to switchautomatically over to the mode of operation that optimizes theeffectiveness of the cardiopulmonary resuscitation.

In a likewise preferred manner, the automatic detection of acardiopulmonary resuscitation may take place by the control andregulation unit being designed to monitor the time curve of the pressureat the patient port during the inspiration phase and the expirationphase and to determine from the time curve of the pressure whether acardiopulmonary resuscitation is being performed on the patient. Thepressure signal, in particular, may be monitored here for regularlyoccurring peaks, and this can be used as a criterion for determiningthat a cardiopulmonary resuscitation is being performed.

In another preferred embodiment, the sensor unit has a sensor, which isdesigned to determine the CO₂ content in the air being exhaled by thepatient during the expiration phase, the control and regulation unitbeing designed to determine from the CO₂ content of the air beingexhaled by the patient whether a cardiopulmonary resuscitation is beingperformed on the patient.

In addition, it is also possible to determine whether a cardiopulmonaryresuscitation is being performed on the patient on the basis of thesignal of a sensor present at the ventilation system for measuring theoxygen saturation in the blood (SPO₂), which can be connected to thepatient.

Finally, the sensor unit may have a sensor that is designed to determinethe oxygen content in the air being exhaled by the patient during theexpiration phase, the control and regulation unit being designed todetermine from the oxygen content in the air being exhaled by thepatient whether a cardiopulmonary resuscitation is being performed onthe patient.

In another preferred embodiment, the ventilation system has a displayunit, which is connected to the control and regulation unit, the controland regulation unit being designed to generate a first alarm message onthe display unit in the first mode operation when a parameter detectedby the sensor unit exceeds or falls below a threshold value, and thecontrol and regulation unit being designed not to generate an alarmmessage or to send a second alarm message different from the first alarmmessage when the parameter detected by the sensor unit falls below orexceeds the threshold value in the second mode of operation.

The fact that the cardiopulmonary resuscitation affects the parametersdetected by the sensor unit, for example, the pressure or the CO₂content, is taken into account by this design. Alarm settings that aremeaningful in the first mode of operation, in which the patient is beingventilated normally, no longer make any sense in the second mode ofoperation during a cardiopulmonary resuscitation, so that an alarmgenerated by the display unit is no longer meaningful, but it ratherdisturbs the user. This is taken into account in this embodiment.

If the display unit has acoustic signal device for sending an acousticalarm, the first alarm message comprising a first acoustic alarm, thesecond alarm message cannot comprise an acoustic alarm, or it maycomprise a second acoustic alarm, which is different from the first oneand whose volume is reduced relative to the first acoustic alarm.

In another preferred embodiment or combined with the embodimentexplained above, a display unit is provided, and the control andregulation unit is designed to monitor a parameter detected by thesensor unit in the second mode of operation and to generate a firstmessage by the display unit when the parameter falls below a firstthreshold value and to generate a second message by the display unitwhen the parameter exceeds the first threshold value and falls below asecond threshold value that is higher than the first threshold value,and to generate a third message by the display unit when the parameterexceeds the second threshold value, the first, second and third messagesbeing different from one another. In particular, the sensor unit mayhave a sensor that is designed to determine the CO₂ content in the airbeing exhaled by the patient during the expiration phase, the CO₂content in the air being exhaled by the patient being the parameterbeing monitored.

In such an embodiment, the user is informed by the different messages ofwhether the parameter in question is in a possibly desired range betweenthe first and second threshold values or outside that range. In case ofthe CO₂ in the exhaled air, the first threshold value may be selectedsuch that a measured value below that threshold indicates that thecardiopulmonary resuscitation shows no sufficient effect and it maypossibly not being carried out correctly. The second threshold value maybe selected such that if the measured CO₂ content is above it, thecardiopulmonary resuscitation can be ended because the patient canbreathe on his own. The second message now shows that thecardiopulmonary resuscitation is being performed correctly but must becontinued, while the third message shows to the user that thecardiopulmonary resuscitation can be ended.

As an alternative to a parameter of the breathing air, a sensor formeasuring the oxygen saturation in the blood (SPO₂), which may beconnected to the patient, may be provided at the ventilation system forthe above-mentioned purpose, the control and regulation unit beingdesigned to monitor the oxygen saturation in the blood (SPO₂) in thesecond mode of operation and to trigger a first message by the displayunit when the oxygen saturation in the blood (SPO₂) falls below a firstthreshold value, to trigger a second message by the display unit whenthe oxygen saturation in the blood (SPO₂) exceeds the first thresholdvalue and falls below a second threshold value that is higher than thefirst threshold value, and to trigger a third message by the displayunit when the oxygen saturation in the blood (SPO₂) exceeds the secondthreshold value, the first, second and third messages being differentfrom one another.

Finally, the ventilation system may have a device for automaticallyperforming a cardiopulmonary resuscitation, which device is connected tothe control and regulation unit, the control and regulation unit beingdesigned (configured) to switch over from the first to the second modeof operation in case of activation of the device for performing acardiopulmonary resuscitation.

In addition, it is possible that the ventilation system has a voltagegenerator for generating voltage pulses, which is connected to thecontrol unit, the voltage generator being provided with electrodes forconnection to a patient.

According to the present invention, the ventilation method describedbelow can, in addition, be carried out, a ventilation system used forthis having the following components:

A gas supply device; a tube arrangement, the tube arrangement having apatient port for connection to a patient in order to send gas from thegas supply unit to the patient and to remove gas being exhaled by thepatient; gas flow-controlling device from the gas supply device to thepatient port and for guiding the gas flow away from the patient port;and a sensor unit, which is arranged in the tube arrangement and is setup to detect parameters of the gas supplied to the patient and exhaledby the patient.

In a first mode of operation, the gas flow-controlling device areactuated according to the present invention during an expiration phasesuch that the pressure of the gas being exhaled by the patient at thepatient port is described by a first curve, and gas flow-controllingdevice are actuated during an inspiration phase such that the pressureof the gas being supplied to the patient at the patient port isdescribed by a second curve, the expiration phase and the inspirationphase following one another alternatingly continuously.

Further, there is a second mode of operation according to the presentinvention, in which the gas flow-controlling device are actuated duringthe expiration phase such that the pressure of the gas being exhaled bythe patient at the patient port is described, at least during a sectionof the expiration phase, by a third curve, which is increased comparedto the first curve, and the gas flow-controlling device are actuatedduring an inspiration phase such that the pressure of the gas beingsupplied to the patient at the patient port is described, at leastduring a section of the inspiration phase, by a fourth curve which isreduced compared to the second curve.

Finally, there is a switch over from the first to the second mode ofoperation when a cardiopulmonary resuscitation is performed.

As was already explained in connection with the ventilation systemaccording to the present invention, whether a cardiopulmonaryresuscitation is being performed on the patient is taken into account inthe method according to the present invention as well. Ifcardiopulmonary resuscitation is being performed, the second mode ofoperation can be activated, in which the pressure is increased at leastin some sections during the expiration phase in order to make itdifficult for the heart to yield into the area of the lungs. Inaddition, the pressure is reduced during the inspiration phase at leastin some sections relative to the first mode of operation, which takesplace during a normal ventilation, in order to achieve that a largeamount of blood will flow into the cardiac vessels.

In a preferred embodiment of the ventilation method according to thepresent invention, the expiration phase and the inspiration phase havetwo consecutive partial phases in the second mode of operation, thepressure of the gas being exhaled by the patient at the patient portbeing described in the first partial phase of the expiration phase bythe third curve, the pressure of the gas being exhaled by the patient atthe patient port being described in the second partial phase of theexpiration phase by a curve corresponding to the first curve, thepressure of the gas being supplied to the patient at the patient portbeing described in the first partial phase of the inspiration phase bythe fourth curve, and the pressure of the gas being supplied to thepatient at the patient port being described during the second partialphase of the inspiration phase by a curve corresponding to the secondcurve. The pressure curve is modified only at the start of theexpiration phase and the inspiration phase in the second mode ofoperation in this embodiment, while the curve otherwise remainsunchanged compared to the first mode of operation.

Further, the gas flow-controlling device may be actuated in oneembodiment of the method such that the third and/or fourth pressurecurve are obtained by increasing or decreasing a desired pressure value.

In an alternative hereto, the method according to the present inventionmay be carried out with a ventilation system whose tube arrangement hasa breathing gas outlet line, which leads away from the patient port andcan be opened and closed in relation to the patient port by anexpiration valve, as well as a breathing gas supply line, which leadsfrom the gas supply device to the patient port and can be opened andclosed in relation to the patient port by an inspiration valve. Theexpiration valve can then be actuated in the second mode of operationsuch that it is opened with a time delay relative to the start of theexpiration phase and that the inspiration valve is actuated such that itis opened with a time delay relative to the start of the inspirationphase.

The pressure increase and the pressure reduction at the start of theexpiration phase and inspiration phase is achieved in this embodiment bythese being achieved by the breathing of the patient.

Furthermore, the method according to the present invention may bedesigned such that it is determined from the parameters detected by thesensor unit whether a cardiopulmonary resuscitation is being carried outon a patient connected to the patient port, and the second mode ofoperation is selected when parameters corresponding to a cardiopulmonaryresuscitation are present. In particular, the time curve of the pressureat the patient port can be monitored during the inspiration phase andthe expiration phase, and it is determined from the time curve of thepressure whether a cardiopulmonary resuscitation is being carried out onthe patient.

As an alternative or in addition, a sensor, which is designed todetermine the CO₂ content in the air being exhaled by the patient duringthe expiration phase, may be provided in the ventilation system, and itis determined from the CO₂ content in the air being exhaled by thepatient whether a cardiopulmonary resuscitation is being performed onthe patient. It is, however, also conceivable that, in addition or as analternative, the ventilation system has a sensor for measuring theoxygen saturation in the blood (SPO₂), which may be connected to apatient, and it is determined from the value of the oxygen saturation inthe blood whether a cardiopulmonary resuscitation is being carried outon the patient. Finally, it is also possible that the sensor unit has asensor that is designed to determine the oxygen content in the air beingexhaled by the patient during the expiration phase, and it is thendetermined from the oxygen content in the air being exhaled by thepatient whether a cardiopulmonary resuscitation is being performed onthe patient.

In any case, it is achieved in case of these possibilities that theoperating method for a ventilation system is designed such that itchanges automatically over from the first mode of operation intended fornormal ventilation to the second mode of operation intended forcardiopulmonary resuscitation when the presence of resuscitationmeasures is detected.

In another embodiment, the method according to the present invention maybe carried out with a ventilation system that has a display unit,wherein a first alarm message is generated on the display unit in thefirst mode of operation when a parameter detected by the sensor unitexceeds or falls below a threshold value, and no alarm message isgenerated or a second alarm message differing from the first alarmmessage is generated in the second mode of operation when the parameterdetected by the sensor unit exceeds or falls below the threshold value.In particular, the display unit may have acoustic signal device forgenerating an acoustic alarm, the first alarm message comprising a firstacoustic alarm and the second alarm message comprising no acoustic alarmor comprising a second acoustic alarm, which is different from the firstone and whose volume is reduced compared to the first acoustic alarm. Itis achieved in this embodiment of the method according to the presentinvention that when the second mode of operation intended for acardiopulmonary resuscitation is selected, a user is no longerconfronted with alarm messages for which the necessary measures hadalready been taken by initiating the cardiopulmonary resuscitation. Thealarm messages are consequently adapted in this embodiment of the methodautomatically to the changed situation caused by the cardiopulmonaryresuscitation in order to relieve the user of the burden of having tobother about alarms whose cause is already being dealt with actively.

Furthermore, the method according to the present invention may bedesigned such that a parameter detected by the sensor unit is monitoredin the second mode of operation and a first message is generated by thedisplay unit when the parameter falls below a first threshold value, asecond message is generated by the display unit when the parameterexceeds the first threshold value and falls below a second thresholdvalue that is higher than the first threshold value, and a third messageis generated by the display unity when the parameter exceeds the secondthreshold value, the first, second and third messages being differentfrom one another.

In particular, the ventilation system may be designed in this embodimentof the method such that the sensor unit has a sensor, which is designedto determine the CO₂ content in the air being exhaled by the patientduring the expiration phase, the CO₂ content in the air being exhaled bythe patient being the monitored parameter. As an alternative, theventilation system may also have a sensor for measuring the oxygensaturation in the blood (SPO₂), which may be connected to a patient, inwhich case the oxygen saturation in the blood (SPO₂) is the monitoredparameter.

When the method is taking place according to this embodiment and thefirst and second threshold values are set properly, a feedback can begiven to a user during the performance of a cardiopulmonaryresuscitation on whether the cardiopulmonary resuscitation is beingcarried out correctly and whether this must be continued. If, forexample, the CO₂ content in the air being exhaled by the patient is usedas the monitored parameter, the first message shows that the desiredeffect is not achieved despite the performance of a cardiopulmonaryresuscitation, so that the performance of the resuscitation measuresshould be checked. When the second message is generated, the CO₂ contentis between the two threshold values, which shows that thecardiopulmonary resuscitation is being carried out in such a manner thata sufficient supply is ensured for the organs. Finally, the thirdmessage, which is generated when the CO₂ content in the breathing air isabove the second threshold value, shows that the patient can breathe onhis own and the cardiopulmonary resuscitation does not have to becontinued.

Finally, the method may also be carried out together with a ventilationsystem that has a device for automatically performing a cardiopulmonaryresuscitation, in which case a switch over is performed from the firstto the second mode of operation when the device for performing acardiopulmonary resuscitation is activated.

A ventilator according to the present invention is designed forperforming the method according to the present invention for operating aventilator which assists cardiopulmonary resuscitation (CPR).

Such a ventilator comprises for this actuators and sensors withcorresponding control elements, which are designed in practice as acentral or non-central control and regulation unit, as well as adisplay, signal generation and operating unit. Additional data inputsand outputs, sensor system or data interfaces, which make it possible toexchange data with other devices or accessory components, may optionallybe provided on this ventilator.

Such a ventilator may be designed in a special embodiment as a so-calledemergency ventilator, a device designed especially for ventilation inemergency situations, for example, in the form of a mobile, portabledevice, which can be operated independently from a power supply voltageand a gas supply. The independence of the emergency ventilator from thepower supply voltage is achieved by the device being equipped withbatteries, for example, rechargeable batteries or primary batteries.

The independence of the emergency ventilator from the gas supply can beachieved by carrying gas or a plurality of gases in pressurized gascylinders, optionally combined with a design with a blower as theventilation drive for providing air as a breathing gas. A nozzlearrangement drawing in ambient air, a so-called ejector, usuallydesigned in the technical embodiment as a so-called Venturi nozzle,combined with a pressurized oxygen gas source, usually designed as apressurized oxygen cylinder, may be used to mix and meter the gases,essentially to mix air and oxygen. A blower drive, embodied technicallyas a radial compressor or as a side channel blower in conjunction withmetering valves for metering and mixing the gases, may be used as analternative hereto. The additional components of the ventilatornecessary for performing and controlling the ventilation of a patient,besides gas supply and electric power supply, include an inspiratorymetering unit designed to be suitable for metering, usually designed asor comprising at least one inspiration valve or an array of a pluralityof valves or valve elements for metering and mixing the quantity of airand the quantity of gas and for setting the patient's airway pressureduring the inspiration phases of the patient. Furthermore, theadditional necessary components of the ventilator include an expiratorymetering unit, designed, for example, as an expiration valve whosedegree of opening is controllable for setting the inspiration andexpiration phases, as well as for setting the patient's airway pressure,the expiration valve may be able to be designed as an internal valve inthe ventilator or as an external expiration valve arranged in the gassupply to the patient.

Additional components of the ventilator according to the presentinvention are sensors for pressure measurements, which are suitable forperforming a pressure measurement and pressure regulation in conjunctionwith the control and regulation unit during inspiration and/orexpiration. Furthermore, sensors for inspiratory/expiratory flowmeasurement are preferably components of the ventilator, which arepreferably suitable for performing a preferred flow measurement, flowrate measurement and/or flow regulation in conjunction with the controland regulation unit. An additional sensor system, which is designed tomonitor the metering and mixing of the gases in conjunction with thecontrol and regulation unit, is preferably additionally present. Thepressure measurement is used here to detect a current ventilationpressure and a curve of the ventilation pressure, which is supplied tothe patient during the inspiration phase, and the current ventilationpressure, which remains as a positive end-expiratory pressure (PEEP) atthe end of the expiration in the patient's lungs. Furthermore, theventilation pressure is used as the actual value whenpressure-controlled ventilation is performed. For example, CPAP(Continuous Positive Airway Pressure), PC-BiPAP (Bi-level PositiveAirway Pressure), PC-AC (Pressure Control-Assist Control), PC-PSV(Pressure Control-Pressure Support Ventilation) are available aspossible pressure-controlled forms of ventilation.

The flow rate determined by means of the preferred flow measurement isused here to detect the actual flow and the curve of the flow rateduring the ventilation. By integrating the current flow values or thecurve of the flow rate, the volume is determined from the flow rate. Itis possible as a result both to determine the patient's appliedrespiratory minute volume (RMV) and to recognize possible leaks in theair supply to the patient by balancing the inspiration and expirationvolumes. Furthermore, the flow rate or the volume determined therefromis used as an actual value when performing a volume-controlledventilation. For example, VC-SIMV (Volume Control-SynchronizedIntermittent Volume Control), VC-MMV (Volume Control-Mandatory MinuteVolume), VC-CMV (Volume Control-Continuous Mandatory Ventilation) areavailable as possible volume-controlled forms of ventilation. This listof the forms of ventilation is only an example at this point and in noway complete and final. In addition, the pressure measurement and theflow measurement during the ventilation make possible thechronologically current monitoring of maximum limits of the ventilationpressure and flow, which should not be exceeded in order to ensure safeventilation. Additional components are an input unit for inputtingparameters, an output unit, for example, in the form of a display screenfor outputting operation and status parameters as well as measuredvalues, as well as for displaying curves and for providing informationto the user. In addition, a sensor or data interface is provided forexchanging data with external devices, with external physiologicalmonitoring devices (physiological monitoring device) or for signal anddata exchange with accessories or sensor systems belonging or assignedto the device or additional accessories or sensor systems and, possiblyalso via the intermediary of additional components for adapting theprotocol and levels, for communication in a data network (intranet, LAN,WLAN, internet). Furthermore, a control and regulation unit is providedfor detecting and processing measured values (flow measurement, pressuremeasurement), for polling the input unit, controlling the output unitand for the general control of the emergency ventilator, as well asespecially for controlling the ventilation with different modes ofoperation of ventilation and different forms of ventilation (modes ofventilation). The parameters transmitted via the input unit forcontrolling the ventilation arise from the diagnostic marginalconditions and the therapeutic considerations of the user, taking theconstitution (gender, age, body weight, height, diagnosis) of thepatient into account, and they yield specifications for the operation ofthe ventilator which assists cardiopulmonary resuscitation (CPR). Therespiration rate (RR), the target pressure of ventilation (P), themaximum pressure amplitude during ventilation, the tidal volume (Vt) andthe I:E ratio, which corresponds to the ratio of the duration ofinspiration to the duration of expiration, are sent as parameters forcontrolling and regulating the ventilator which assists cardiopulmonaryresuscitation to a control and regulation unit. On the one hand, theseparameters can be set by the user as direct set values on a controlunit, and the set values may also be derived from other parameters inanother variant. Furthermore, an alarm and alarm adaptation unit ispresent for monitoring threshold values and tolerance ranges, in whichcorresponding threshold values and one or more tolerance ranges, whichare independent or are in a relation to one another, are preset or setby the user, at times after presetting (default settings) or afterderivation from the parameters, and they are then set by the userdefinitively and finally by acknowledgment/confirmation. Acousticand./or optical alarms are triggered on the ventilator when valuesexceed or fall below the threshold values or if a value leaves one ormore tolerance ranges. Such an alarm and alarm adaptation unit isclosely connected to the display and signal generation unit, the inputunit and the control and regulation unit or is at least partiallyintegrated in it.

A patient is connected to the ventilator and is supplied with breathinggas via a tube system. The tube system comprises an inspiratory branchfor supplying air and fresh breathing gas from the ventilator to thepatient and an expiratory branch for moving spent breathing gas from thepatient to the ventilator. The patient is connected to the ventilatorvia the tube system via a connection piece, preferably a Y-piece forconnecting the inspiratory branch and the expiratory branch.

The control and regulation unit converts the parameters into thenecessary manipulated variables for the pressure and flow regulation andthe actuation of the components of the device, for example, theactuators. At least one inspiratory metering unit, designed, forexample, as an inspiratory metering valve (inspiration valve) and/orventilation drive or as a radial compressor, as well as an expiratorymetering unit, designed, for example, as an expiratory metering valve(expiration valve), are present as actuators in the ventilator.Furthermore, the sensor systems present in the ventilator include atleast one pressure sensor. The at least one pressure sensor ispreferably arranged as an inspiratory pressure sensor in the inspiratorybranch of the ventilator or as an expiratory pressure sensor in theexpiratory branch of the ventilator. An additional pressure sensor isalso preferably present in the ventilator. At least one flow sensor,preferably designed in the form of an inspiratory and/or expiratory flowsensor and/or in the form of a flow sensor located close to the patient,is also preferably present in the ventilator. Due to the conversion ofthe manipulated variables into the actuation of the actuators,especially of the inspiratory and expiratory metering unit, and theinclusion of the sensor system, especially of the inspiratory pressuresensor, and also preferably of the expiratory pressure sensor, and alsopreferably of the inspiratory and/or expiratory flow sensor and/or ofthe flow sensor located close to the patient, the control and regulationunit is able to carry out the ventilation of the patient according tothe settings and the specifications of the user and to monitorcompliance with the specifications and settings. Two fundamentallydifferent tube systems are commonly used in clinical practice. There areso-called “one-tube systems” as well as so-called “two-tube systems.” A“one-tube system” is preferably used on emergency ventilators and ischaracterized in that a single tube , which delivers an inspiratoryair/gas mixture to the patient during inhalation, is led from theventilator to the patient. The expiratory metering valve, via which theair being exhaled by the patient escapes into the surrounding area, isprovided on the connection piece to the patient on the “one-tubesystem.” This metering valve is also frequently called “expiration valvelocated close to the patient” in case of embodiment in a “one-tubesystem.” Furthermore, the expiratory pressure sensor is arranged in theconnection piece. A “two-tube system” is characterized in that two tubesare led from the ventilator to the patient, a first tube delivering theinspiratory air/gas mixture to the patient during inhalation and asecond tube returning the exhaled air to the ventilator. The expiratorymetering valve as well as the expiratory pressure sensor are arranged inthe expiratory branch in the ventilator. It is common to both tubesystems that the expiratory metering valve and the expiratory pressuresensor are arranged close to one another. Therefore, this is especiallyadvantageous because the adjusting element for setting the ventilationpressure and the measuring element for detecting the ventilationpressure can act in a ventilation pressure control circuit without anessential offset in time in relation to one another. It is possible, inprinciple, in a “two-tube system” that an additional pressure sensor isprovided on the connection piece in order to further optimize theventilation pressure control circuit and to make it possible, forexample, to compensate differences in the length of the ventilationtubes, water traps or breathing air humidifiers.

A device according to the present invention is designed especially as amedical ventilator and comprises the following components, which arenecessary as a minimum for the operation of the ventilator which assistscardiopulmonary resuscitation (CPR) and for ventilating a patient:

An inspiratory metering unit, an expiratory metering unit, a control andregulation unit, an alarm and alarm adaptation unit, a display, signalgeneration and operating unit for outputting display values, alarms andsignals to a user and for inputting setting values by the user, at leastone pressure sensor for monitoring threshold values, and a sensor ordata interface for connecting sensors or external devices orphysiological monitoring devices. The control and regulation unit isdesigned in this device according to the present invention tocontinuously detect a current value of a pressure of the at least onepressure sensor, to compare the current value of a pressure with a firstpredetermined value and to actuate the expiratory metering unit suchthat the current value of the pressure corresponds to the firstpredetermined value. The patient is preferably and usually connected tothe medical ventilator by means of a tube system.

In a first embodiment of the device according to the present invention,the control and regulation unit is designed to actuate the expiratorymetering unit and the inspiratory metering unit such that the currentvalue of the pressure is increased during a first phase by a secondpredetermined value relative to a first predetermined value, and toactuate the expiratory metering unit and the expiratory metering unitsuch that the current value of the pressure is reduced relative to thefirst predetermined value by a third predetermined value during a secondphase.

In a second embodiment of the device according to the present invention,at least one additional sensor is present in addition to the at leastone pressure sensor, and the control and regulation unit is designed toreceive a signal of the at least one sensor or of the at least onepressure sensor and to analyze the signal of the at least one sensor orpressure sensor and/or the time curves of the signals of the at leastone sensor or of the at least one pressure sensor, and to determine atleast one sign (CM) activity to determine whether a cardiac massage isbeing performed on the patient.

In another preferred embodiment of the second embodiment of the deviceaccording to the present invention, the control and regulation unit isdesigned to analyze the signal of the at least one sensor and/or thetime curve of the signal and/or the signal of the at least one pressuresensor and/or the time curve of the signal of the at least one pressuresensor to determine a quality index (QIndex-CM) concerning the qualitywith which a cardiac massage is performed. The quality index (QIndex-CM)may preferably be determined by a comparison of an actually detectedsignal of the at least one sensor with at least one predeterminedquality threshold value.

In another preferred variant of the second embodiment of the invention,the device is designed, based on a configuration of the control andregulation unit, to analyze the signal of the at least one pressuresensor and/or from the time curve of the signal of the at least onepressure sensor as a ventilation pressure and/or time curve of theventilation pressure such that a cardiac massage (CM) currently beingapplied is recognized and an operation of the ventilator which assistscardiopulmonary resuscitation (CPR) is automatically started.

In another preferred variant of the second embodiment, the device isdesigned to analyze the ventilation pressure and/or the curve of theventilation pressure such that a current ending of a previously appliedcardiac massage (CM) is recognized and the operation of the ventilatorwhich assists cardiopulmonary resuscitation (CPR) is ended.

The at least one additional sensor is also designed preferably as atleast one physiological sensor. The at least one physiological sensor ispreferably designed as a sensor for detecting a carbon dioxideconcentration (CO₂) in the breathing gas of a patient. The at least onephysiological sensor is also preferably designed as a sensor fordetermining an oxygen saturation (SPO₂) in the blood of a patient.

The at least one additional sensor is preferably designed here as atleast one flow sensor. The at least one flow sensor is also preferablydesigned as an inspiratory flow sensor, expiratory flow sensor or as aflow sensor located close to the patient.

In an special variant of the second embodiment of the device accordingto the present invention, the device is designed by means of the controland regulation unit to analyze the signal of the at least onephysiological sensor and/or a time curve of the signal of the at leastone physiological sensor in order to determine the at least one qualityindex (QIndex-CM) concerning the performance of the cardiac massage(CM).

In a special variant of the second embodiment of the device according tothe present invention, the device is designed by means of the controland regulation unit to use a signal of at least one physiological sensorand/or a time curve of the signal of the at least one physiologicalsensor and/or the signal of the at least one pressure sensor as aventilation pressure and/or the time curve of the signal of the at leastone pressure sensor as the curve of the ventilation pressure in order todetermine the at least one sign (CM activity) that a cardiac massage iscurrently being performed and/or to determine the at least one qualityindex (QIndex-CM) concerning the performance of the cardiac massage(CM).

In another variant of the second embodiment of the device according tothe present invention, the device is designed by means of the controland regulation unit in conjunction with the at least one flow sensordesigned as an expiratory flow sensor, inspiratory flow sensor or flowsensor located close to the patient to use signals of the at least oneflow sensor and/or the time curves of the signals of the at least oneflow sensor in order to determine the at least one sign (CM activity)whether a cardiac massage (CM) is being performed on the patient and/orto determine the at least one quality index (QIndex-CM) concerning theperformance of the cardiac massage (CM).

The physiological sensor according to the likewise preferred embodimentof the second embodiment of the device according to the presentinvention is designed to detect at least one physiological signal as aparameter relevant for the cardiopulmonary resuscitation (CPR). If thephysiological sensor is used as a sensor to determine the at least onesign (CM activity) to determine whether a cardiac massage is beingperformed on the patient, and/or to determine the at least one qualityindex (QIndex-CM) concerning the quality with which the cardiac massageis performed, the term physiological sensor is defined in the sense ofanother preferred embodiment of the second embodiment of the deviceaccording to the present invention as and also comprises any type ofsensor system that provides information concerning the patient's status.The physiological sensor system is characterized in the sense of thepresent invention in that measured physiological variables and signalsof the device according to the present invention are made available.Contrary to this, an operating sensor system in the sense of the presentinvention is characterized in that it detects status variables on theoperating state of the medical ventilator or on the course of theoperation during ventilation, e.g., flow rates, temperatures, pressurevalues. The following list of different physiological sensors andphysiological parameters is by no means complete and final in the senseof the present invention. Physiological parameters detectable by meansof physiological sensors in the sense of the present invention for useto determine the quality index (QIndex-CM) of the cardiac massage and/orto determine a sign (CM activity) to determine whether and how a cardiacmassage is being performed and/or for an analysis at the start or at theend of the operation of a ventilator which assists cardiopulmonaryresuscitation (CPR) are essentially:

a carbon dioxide concentration in the breathing gas (CO₂) of thepatient,

an oxygen saturation in the blood (SPO₂) of the patient.

The physiological sensor is designed in a preferred manner in thisadditional preferred embodiment of the second embodiment as a sensor oras an external physiological monitoring device (capnometer) to detectthe concentration of carbon dioxide in the gas being exhaled by thepatient. In a first variant, the carbon dioxide concentration (CO₂) inthe air being exhaled by the patient is detected and measured by adefined quantity of air being delivered continuously from the connectionpiece via a suction line to the external physiological monitoring deviceand/or to the physiological sensor and being analyzed in the externalphysiological monitoring device and/or the physiological sensor. Thismeasurement method is called “sidestream measurement,” and sensorsdesigned suitably for this are called “CO₂ sidestream sensors.” In asecond variant of the detection and measurement of the carbon dioxideconcentration (CO₂) in the air being exhaled by the patient, thedetection of the carbon dioxide concentration (CO₂) is performedcontinuously with a physiological sensor at the connection piece. Thephysiological sensor preferably operates in the usual embodimentaccording to an infrared optical measurement method in a transmittedlight operation directly at the connection piece in the path of the gasto the patient. This measurement method is called “CO₂ mainstreammeasurement” and a sensor designed suitably for this is called a CO₂mainstream sensor.”

The physiological sensor at the connection piece may also contain at theconnection piece in a technical embodiment the components necessary forthe measurement, analysis and determination of the carbon dioxideconcentration (CO₂) as well as for the display thereof, but in anothertype of technical embodiment, the components for the analysis,determination and display of the carbon dioxide concentration (CO₂) mayalso be arranged in an eternal physiological monitoring device, which isconnected to the physiological sensor by means of a data and/or energylink. A flow sensor located close to the patient is preferably arrangedin this variant at the connection piece to the patient to balance theinhalation and exhalation volume flows and—by means of integration overtime—to balance inhalation and exhalation volumes.

In another preferred form of the additional variant of the secondembodiment of the device according to the present invention, the deviceis designed (configured), by means of the control and regulation unit,to derive further variables to determine the at least one indication (CMactivity) to determine that a cardiac massage is currently beingperformed, as well as to determine the at least one quality index(QIndex-CM) concerning the performance of the cardiac massage (CM), fromthe signals and/or signal curves of the inspiratory and/or expiratoryflow sensor, as well as from the signals of the physiological sensorand/or from the time curve of the signal of the at least onephysiological sensor. Such a derived variable is, for example, anexpiratory volume or a minute volume of carbon dioxide (MVCO₂),determined from measured values of the flow sensor located close to thepatient in conjunction with the measured values of the sensor fordetecting a carbon dioxide concentration (CO₂) in the breathing gas,which is preferably designed for this as a “CO₂ mainstream sensor.”

The physiological sensor is designed for this as a sensor for detectinga carbon dioxide concentration (CO₂) in the breathing gas. This minutevolume of carbon dioxide (MVCO₂) can be determined by means of anintegration over time of volume flows detected by means of the volumeflow sensors in conjunction with the sensor for detecting a carbondioxide concentration in the breathing gas.

In this additional preferred embodiment, the physiological sensor ispreferably designed as a sensor or as an external physiologicalmonitoring device (pulse oximeter) for detecting and determining theoxygen saturation (SPO₂) in the blood of the patient.

The oxygen saturation (SPO₂) in the blood is preferably detected andmeasured non-invasively in clinical practice by means of anoptical/infrared-optical measurement method, the so-called pulseoximetry in the transmitted-light method, for example, on the finger,toe or earlobe of the patient.

By means of the carbon dioxide concentration (CO₂) in the breathing gasand/or the oxygen saturation (SPO₂) in the blood, the device accordingto the present invention is preferably able to determine at each time inwhat manner a cardiopulmonary resuscitation (CPR) being currentlyperformed is taking place for the patient and/or whether it iseffective.

Additional physiological parameters in the sense of the presentinvention are:

-   -   an oxygen concentration (O2) in the breathing gas of the        patient,    -   a carbon dioxide partial pressure (CO2) in the blood of the        patient,    -   an oxygen partial pressure in/under the cutaneous tissue        (transcutaneously) of the patient,    -   a carbon dioxide partial pressure in the cutaneous tissue        (transcutaneously) of the patient,    -   an oxygen concentration (O2) having average activity in the        patient's lungs,    -   a diastolic blood pressure value of the patient determined        invasively or non-invasively,    -   a systolic blood pressure value of the patient determined        invasively or non-invasively,    -   invasively detected blood gas values of the patient (on-site        blood gas analysis),    -   a heart beat or a pulse rate of the patient,    -   a cardiological signal, e.g., ECG signals, EEG signals, EMG        signals,    -   a sonographic signal, for example, of a blood vessel of the        patient, and    -   a tomographic signal, for example, of the lungs of the patient.

Furthermore, variables derived from the above-mentioned physiologicalvariables as well as variables that are derived from the latter and/orcombined with one another are also covered in the sense of the presentinvention. The physiological sensor is preferably connected directly tothe device according to the present invention by means of the sensor anddata interface.

In another preferred variant, the physiological sensor is connected toan external device, which is connected to the device according to thepresent invention by means of the sensor and data interface. The dataand/or measured values of the physiological sensor connected to theexternal device are transmitted via the sensor and data interface to thedevice according to the present invention.

The quality index (QIndex-CM) of the performance of the cardiac massagemay be determined here in a suitable manner by a comparison of acurrently detected signal of the physiological sensor with at least onepredetermined quality threshold value. In an embodiment of thephysiological sensor as a sensor for detecting the carbon dioxideconcentration in the breathing gas, a carbon dioxide concentration of,for example, of 10 mmHg with a variation of +/−2 mmHg is a valuesuitable for the determination of the quality index (QIndex-CM) forpractical use in emergency medicine as a predetermined quality thresholdvalue. A value above 10 mmHg corresponds here to the performance of acardiac massage being performed properly for resuscitating the patient.

In one embodiment of the physiological sensor as a sensor for detectingand determining the oxygen saturation (SPO₂) in the blood of thepatient, a value above 70% with a variation of +/−10% is a valuesuitable for the determination of the quality index (QIndex-CM) forpractical use in emergency medicine as a predetermined quality thresholdvalue.

In another preferred variant of the second embodiment of the deviceaccording to the present invention, the device is designed by means ofthe alarm and alarm adaptation unit in conjunction with the display andsignal generation unit to send a message to the user when an actualvalue falls below a first predetermined threshold value of the signal ofthe physiological sensor, indicating that a changeover to the operationof the ventilator with assisted cardiopulmonary resuscitation (CPR) isrecommended for the current situation of the patient, and an input is tobe expected from the user to start the operation of the ventilator withassisted cardiopulmonary resuscitation (CPR). Furthermore, the messageto the user may preferably contain an instruction that the user shallperform cardiopulmonary resuscitation (CPR) with cardiac massage on thepatient in the patient's current situation.

In another preferred embodiment of the second embodiment, the device isdesigned by means of the control and regulation unit to analyze thesignal of the physiological sensor such that the method for operating aventilator with assisted cardiopulmonary resuscitation (CPR) will bestarted.

In another preferred embodiment of the second embodiment, the device isdesigned by means of the control and regulation unit to analyze thesignal of the physiological sensor such that the method for operating aventilator with assisted cardiopulmonary resuscitation (CPR) will beended.

The device is designed in a special variant of the second embodiment tostart the operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR) automatically, i.e., automatically, preferablywithout a further user interaction, besides the above-mentioned messageto the user, when an actual value falls below the first predeterminedthreshold value of the signal of the physiological sensor.

In one embodiment of the physiological sensor as a sensor for detectingthe carbon dioxide concentration in the breathing gas, a value of, forexample, 20 mmHg with a variation of +/−2 mmHg is a value suitable forautomatically starting the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR) for practical use in emergencymedicine as a first predetermined threshold value. If the physiologicalsensor is designed as a sensor for detecting and determining the oxygensaturation (SPO₂) in the blood of the patient, a value of, for example,60% with a variation of +/−5% is a value suitable for automaticallystarting the operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR) for practical use in emergency medicine as a firstpredetermined threshold value.

In another preferred variant of the second embodiment, the device isdesigned by means of the control and regulation unit to analyze thesignal of the physiological sensor so as to end the operation of theventilator with assisted cardiopulmonary resuscitation (CPR)automatically, i.e., automatically, preferably without further userinteraction, when an actual value exceeds a second predeterminedthreshold value.

In an embodiment of the physiological sensor as a carbon dioxide sensorfor detecting the carbon dioxide concentration in the breathing gas, avalue of, for example, 40 mmHg with a variation of +/−2 mmHg is a valuesuitable for automatically ending the operation of the ventilator withassisted cardiopulmonary resuscitation (CPR) for practical use inemergency medicine as a second predetermined threshold value.

In an embodiment of the physiological sensor as a sensor for detectingand determining the oxygen saturation (SPO₂) in the blood, a value of,for example, 90% with a variation of +/−5% is a value suitable forautomatically ending the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR) for practical use in emergencymedicine as a second predetermined threshold value.

Indicating the carbon dioxide concentration in the breathing gas as apartial pressure in the “mmHg' unit is common in medical and clinicalpractice. Indications or conversion forms into other units of pressure(hPa, mbar, cmH₂O, as well as indications in concentrations (%) are alsocovered in an equivalent manner in the sense of the present invention.Indicating the oxygen saturation (SPO₂) as a concentration value in (%)is common practice in medical and clinical practice. Indications inother units or conversion forms of the partial pressure (mmHg, hPa,mbar, cmH₂O) are also covered in an equivalent manner in the sense ofthe present invention.

The ventilation pressure or the time curve of the ventilation pressuremay be analyzed to recognize a cardiac massage (CM) being currentlyapplied, for example, by means of a comparison of the shape of the curvedescribing the current changes over time in the ventilation pressurewith a usual curve describing the changes in the ventilation pressure.The usual curve of the ventilation pressure is selected either such thatthe curve is free from additional cyclic rhythmic pressure peaks typicalof the effect of the cardiac massage (CM) or such that the curve hascyclic rhythmic additional pressure peaks typical of the effect of thecardiac massage (CM). It is then possible to recognize by a comparisonof the curves, for example, by a subtraction with preceding and/orsubsequent filtering and standardization, whether or not a cardiacmassage (CM) is currently just being performed.

A cardiac massage (CM) being currently applied can be recognizedaccording to the above-described embodiments for recognizing, startingor ending the operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR) in such a form that the changes caused by thecardiac massage (CM) currently being applied in the signal and/or in thecurve describing the signal of the at least one pressure sensor aredetermined. The signal or the time curve of the signal of the at leastone pressure sensor represents the ventilation pressure and/or the timecurve of the ventilation pressure. The changes of the signal or on thetime curve of the signal of the at least one pressure sensor are visibleand detectable on the curve of the ventilation pressure as increases inamplitude in the chronological rhythm at which the cardiac massage (CM)is carried out. The increase in amplitude for a predetermined minimumduration of the amplitude increase as an absolute minimum duration or asa relative minimum duration in relation to the respiration rate, apredetermined minimum extent of the amplitude increase as an absolutepressure rise or as a relative pressure rise in relation to the curvedescribing the ventilation pressure, as well as combinations of theabove-mentioned amplitude/duration criteria with one another may be usedas possible criteria for recognizing a cardiac massage (CM) currentlybeing applied.

Some values is mentioned for this below as an example. The absoluteminimum duration of the amplitude increase on the signal of the at leastone pressure sensor is obtained as a time of 0.2 sec to 0.5 sec as arange meaningful for clinical practice for recognizing that a cardiacmassage (CM) is currently being applied.

In another preferred embodiment of the second embodiment, the device isdesigned to analyze the signal of the physiological sensor and/or thetime curve of the signal of the physiological sensor and/or the signalof the at least one pressure sensor and/or the time curve of the signalof the at least one pressure sensor, to recognize a cardiac massage (CM)currently being applied, and to automatically start the operation of theventilator with assisted cardiopulmonary resuscitation (CPR).

In another preferred embodiment of the second embodiment of the deviceaccording to the present invention, the control and regulation unit isdesigned to analyze the signal of the physiological sensor and/or of thetime curve of the signal of the physiological sensor and/or the signalof the at least one pressure sensor and/or the time curve of the signalof the at least one pressure sensor, to recognize a current ending of acardiac massage (CM) being applied, and to automatically end theoperation of the ventilator with assisted cardiopulmonary resuscitation(CPR).

In another preferred embodiment of the second embodiment of the deviceaccording to the present invention, the control and regulation unit isdesigned to analyze the signal of the physiological sensor and/or thetime curve of the signal of the physiological sensor and/or the signalof the at least one pressure sensor and/or the time curve of the signalof the at least one pressure sensor and/or the signal of the at leastone flow sensor and/or the time curve of the signal of the at least oneflow sensor to determine the at least one sign (CM activity) of whethera cardiac massage is being performed on the patient and/or to determinea quality index (QIndex-CM) concerning the quality with which a cardiacmassage is performed.

In another preferred embodiment of the second embodiment, the device isdesigned to analyze the signal of the physiological sensor and/or thetime curve of the signal of the physiological sensor, the signal of theat least one flow sensor and/or the time curve of the signal of the atleast one flow sensor and/or the signal of the at least one pressuresensor as a ventilation pressure and/or the time curve of the signal ofthe at least one pressure sensor as a curve of the ventilation pressure,to recognize a cardiac massage (CM) currently being applied, and toautomatically start the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR).

In another preferred embodiment of the second embodiment of the deviceaccording to the present invention, the control and regulation unit isdesigned to analyze the signal of the physiological sensor and/or thetime curve of the signal of the physiological sensor, the signal of theat least one flow sensor and/or the time curve of the signal of the atleast one flow sensor and/or the signal of the at least one pressuresensor as a ventilation pressure and/or the time curve of the signal ofthe at least one pressure sensor as a curve of the ventilation pressure,to recognize a current ending of a cardiac massage (CM) being applied,and to automatically end the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR).

In a preferred embodiment of the second embodiment of the deviceaccording to the present invention, the alarm and alarm adaptation unitis designed, in conjunction with the display and signal generation unitand the control and regulation unit, to output the at least one sign (CMactivity) and/or the at least one quality index (QIndex-CM) to the user.

In a preferred embodiment of the second embodiment of the deviceaccording to the present invention, the alarm and alarm adaptation unitis designed, in conjunction with the display and signal generation unitand the control and regulation unit, to analyze the signal of the atleast one physiological sensor such that a message is sent to the userwhen a current value falls below a first predetermined threshold value.

In a preferred embodiment of the second embodiment of the deviceaccording to the present invention, the alarm and alarm adaptation unitis designed, in conjunction with the display and signal generation unitand the control and regulation unit, to analyze the signal of the atleast one physiological sensor such that a message is sent to the userwhen a current value exceeds a second predetermined threshold value.

In a preferred embodiment of the first or second embodiment of thedevice according to the present invention, the alarm and alarmadaptation unit is designed, together with the display and signalgeneration unit, to change an alarm generation on the ventilator. Apreferred change of an alarm generation on the ventilator is to delay orto suppress the generation of at least one alarm for at least onemeasured value or for at least one measured variable or for at least oneevent or to vary the volume with which the at least one alarm isgenerated for the at least one measured value or for the at least onemeasured variable or for the at least one event. The alarm and alarmadaptation unit is designed in this preferred embodiment of the first orsecond embodiment of the device according to the present invention tomanage and prioritize the alarms and to partially, temporarily or fullysuppress the sending of alarm to the user as well as to vary the volumeof the alarm. An adaptation of the alarms to the patient's situation ispresent for this in the alarm and alarm adaptation unit in order to makeit possible to adapt, for example, the volume of the acoustic alarms tothe situation, especially to increase or decrease it. A periodic,temporary, partial suppression, delay, skipping, fading out or switchingoff of alarms is defined in the sense of the present invention as anymeasure and also covers the circumstance that an alarm based on ameasured signal, on the fact that a measured value exceeds or fallsbelow a threshold value or based on an event or incident (e.g., anaccidental disconnection of a sensor) during the conventional operationand an alarm provided in the course of the ventilation during theoperation of the ventilator with assisted cardiopulmonary resuscitation(CPR) is not sent directly to the user. The alarm and alarm adaptationunit is designed such that the type of partial, temporary or fullsuppression takes place as a function of the current operation of theventilator (ventilation mode). Additional threshold values and toleranceranges, for example, ventilation pressure, flow rate, inspiratory andexpiratory volumes, respiratory minute volume, are monitored in thealarm and alarm adaptation unit and made available to the user as atleast one signal generation, besides the threshold values and toleranceranges that correspond to the parameters for the control and regulationof ventilation and are derived therefrom, for monitoring measured valuesand for monitoring measured values and measured variables derived frommeasured values. An at least one signal generation is defined in thesense of the present invention such that an alarm signal is generatedoptically or acoustically, optically and acoustically simultaneously orwith a time offset and/or that a further or additional external signalgeneration is carried out by the alarm being available in the form of anelectric signal on an analog or digital, wired or telemetric datainterface.

In another preferred variant of the first or second embodiment of thedevice according to the present invention, the alarm and alarmadaptation unit is designed, in conjunction with the control andregulation unit, to change the alarm limits that are active and relevantduring the operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR) on the basis of the alarm limits set originallyduring the operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR). The alarm limits set originally were set, forexample, by the user before the start of the operation of the ventilatorwith assisted cardiopulmonary resuscitation (CPR). The change of thealarm limits caused, in a further preferred and suitable manner, that analarm is not sent to the user for at least one measured value, for atleast one measured variable or for at least one event.

The alarm and alarm adaptation unit also preferably uses for this theamplitude increases in the chronological rhythm at which the cardiacmassage (CM) is performed on the signal of the at least one pressuresensor or on the time curve of that signal to change the alarm limitsfor the recognition of the performance of the cardiac massage (CM).

The list in the following table contains some exemplary alarm limits andmeasured variables:

RMV-High A target value of the respiratory minute volume preset by theuser is exceeded RMV-Low A target value of the respiratory minute volumepreset by the use is not reached Paw-High A target value of the maximumventilation pressure preset by the user is exceeded etCO₂-Low A targetvalue of the end-tidal carbon dioxide concentration (CO₂) preset by theuser is not reached etCO₂-High A target value of the end-tidal carbondioxide concentration (CO₂) preset by the user is exceeded F_(spon)-HighA limit value of a spontaneous respiration rate preset by the user isexceeded PEEP-Low A limit value of a positive end-expiratory pressure(PEEP) preset by the user is not reached Pressure The ventilatorregulates to a pressure limitation Limited V_(T)-not- A desired value ofa tidal volume (V_(T)) preset by reached the user is not reached

The method according to the present invention for assistingcardiopulmonary resuscitation (CPR) and the device according to thepresent invention for carrying out the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR) make it possible toventilate a patient under the influence of the simultaneous effect of acardiac massage (CM) on the detection of the ventilation pressure. Thetechnical effect of the cardiac massage (CM) applied from the outside onthe ventilator and on the operation and on the guarantee of theoperational safety corresponds to a modulation of an interferencevariable on the control circuit for controlling the ventilation pressureduring the ventilation.

It is ensured according to the present invention that, on the one hand,a regulated ventilation that is advantageous for the patient isguaranteed during simultaneous compression of the chest cavity and, onthe other hand, that the ventilation is carried out in such a way thatthe inflow and outflow of blood to the heart due to the cardiac massage(CM) is not adversely affected by the ventilation.

The method according to the present invention for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR) and the deviceaccording to the present invention for carrying out the method foroperating a ventilator which assists cardiopulmonary resuscitation (CPR)make it possible both that the ventilation by the ventilator bringsabout an efficient exchange of air in the patient's lungs and can becarried out efficiently during cardiac massage (CM) and that theefficiency of the cardiac massage (CM) with an efficient exchange ofblood from the heart into the patient's body is not adversely affectedby the ventilation and the patient will thus return as a result into astable state with spontaneous cardiovascular function after a relativelyshort duration of the cardiopulmonary resuscitation (CPR).

The application of the method according to the present invention toassist cardiopulmonary resuscitation (CPR) causes that at the end of theinspiration and before the start of expiration by the patient, a volume,which is larger than the volume which would fill the patient's lungs atthe end of the inspiration with the application of a ventilation with anormal ventilation mode, i.e., with a mode of ventilation withoutassisted cardiopulmonary resuscitation (CPR), will fill the patient'slungs, so that the lungs fill a part of the chest cavity and thus thepossibility that the heart would yield in the chest cavity duringcompression by the cardiac massage (CM) is reduced and the best possibledelivery of the blood from the heart to the body parts, especially tothe brain, is thus brought about by the compression.

The application of the method according to the present invention ofassisting cardiopulmonary resuscitation (CPR) causes that at the end ofthe expiration and before the start of the inspiration by the patient,the lungs are filled essentially only with a volume that correspondsessentially only to the volume of the functional residual capacity, sothat a reduced residual volume will remain in the lungs compared to thecase of ventilation with a normal mode of ventilation, withoutassistance of cardiopulmonary resuscitation (CPR), so that the backflowof the blood from the body to the heart is assisted during thedecompression of the chest cavity.

In one embodiment according to the present invention of the method forassisting cardiopulmonary resuscitation (CPR), a ventilator is operatedaccording to the present invention according to a method for operationwith mandatory ventilation of a patient and with assistedcardiopulmonary resuscitation (CPR). The ventilator comprises here anexpiration valve, a pressure sensor, a ventilation drive and a controland regulation unit.

It is advantageous for an optimal regulation of the ventilation pressurethat is comfortable for the patient that pneumatic effects, for example,pressure changes brought about by an adjustment of the degree of openingof the expiration valve, can be detected by the pressure sensor in astimely a manner as possible and effects due to propagation paths andpropagation times of pressure changes based on gas species-specificsound velocities are more or less negligible. The pressure sensor istherefore preferably arranged on or in the immediate vicinity of theexpiration valve.

If a pneumatic connection of the ventilator is established with aso-called “two-tube system,” the pressure sensor and the expirationvalve are arranged close to one another in the ventilator itself. If apneumatic connection of the ventilator is established with a so-called“one-tube system,” the pressure sensor and the expiration valve arearranged close to one another on the connection piece, the so-called“Y-piece” to the patient.

The method for operating the ventilator which assists cardiopulmonaryresuscitation (CPR) is designed as a continuously repeating sequence ofat least two phases of a ventilation. The at least two phases aredesigned as a first phase and a second phase. In this operation of theventilator with assisted cardiopulmonary resuscitation (CPR), a currentvalue of a pressure is continuously determined. This current value of apressure is representative of a current airway pressure of the patient.The current pressure value determined is continuously compared with afirst predetermined value in the control and regulation unit. Thecontrol and regulation unit controls the inspiration valve and/or theexpiration valve on the basis of the result of the comparison such thatthe deviation between the first predetermined value and the currentpressure value is minimized, so that the current pressure valvecorresponds to the first predetermined pressure value. A slightdeviation between the first predetermined pressure value and the currentpressure value arises from the residual deviation due to technicalcauses in a control circuit, such as those that are always present inall technical regulating units for a functional regulation.

An initial pressure is increased relative to the first predeterminedvalue by the end of the first phase by a second predetermined value inthe first phase of the at least two phases of ventilation.

A pressure increase in the range of 5 hPa to 10 hPa is obtained as ameaningful range for practice for the second predetermined value.

An initial pressure is reduced relative to the first predetermined valueat the start of the second phase by a third predetermined value in thesecond phase of the at least two phases of ventilation.

A pressure reduction in the range of 2 hPa to 5 hPa is obtained as ameaningful range for practice for the third predetermined value.

In a preferred embodiment, the first phase of the ventilationcorresponds at least partially to an expiration phase of the patient andthe second phase of the ventilation corresponds at least partially tothe inspiration phase of the patient.

In another preferred embodiment of the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR), provisions are madefor the at least two phases of ventilation to form altogether fourpartial phases of ventilation, the first phase of the ventilation beingdivided into a first partial phase and a second partial phase, the firstpartial phase of the ventilation taking place in time before the secondpartial phase of the ventilation, and the second phase of theventilation being divided into a third partial phase of the ventilationand a fourth partial phase of the ventilation, and the third partialphase of the ventilation taking place before the fourth partial phase ofthe ventilation.

In a special variant, the initial pressure is increased by a secondpredetermined value relative to the first predetermined value in thefirst partial phase of the ventilation, and the initial pressure isreduced by a third predetermined value relative to the firstpredetermined value in the third partial phase of the ventilation.

In another embodiment of the method for operating a ventilator whichassists cardiopulmonary resuscitation (CPR), an increase in the initialexpiratory pressure level and hence an increase in the air-filled volumeof the patient's lungs is brought about by increasing the ventilationpressure at the start of the expiration phase by a desired pressurevalue being briefly increased in the pressure control circuit of themechanical ventilation. As a result, the air-filled lungs fill a part ofthe chest cavity and thus reduce the possibility for the heart to yieldin the chest cavity during a compression by the cardiac massage (CM)during the performance of the method for operating a ventilator withassisted cardiopulmonary resuscitation (CPR). This supports theefficiency of the cardiac massage (CM).

The increase in the initial expiratory pressure level is achieved by atime delay with which the expiration valve opens at the start of theexpiration phase in another preferred variant. This delay of the openingof the expiration valve at the start of the expiration phase correspondsto a prolongation of the inspiration phase.

In an especially preferred variant, the desired pressure value isbriefly increased by the ventilation control in the pressure controlcircuit of the mechanical ventilation and the expiration valve isadditionally opened with a delay, so that there will be a greaterincrease in the initial expiratory pressure level at the start of theexpiration phase.

In another preferred embodiment of the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR), a reduction of aninitial inspiratory pressure level in the patient's lungs and thegeneration of a slight vacuum in the lungs in relation to the ambientpressure is achieved by the supply of fresh breathing air being delayedin time at the beginning of the inspiration phase by delaying theopening of the inspiration valve. The pressure in the chest cavity isthus reduced when the method for operating a ventilator with assistedcardiopulmonary resuscitation (CPR) is carried out, so that the backflowof the blood from the body to the heart during the decompression of thechest cavity is assisted.

In another preferred embodiment of the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR), the operation of theventilator with assisted cardiopulmonary resuscitation (CPR) is switchedon and/or off by an activating device. Such an activating device ispreferably designed as a control element or switching element of theventilator. The user is enabled by means of this control element orswitching element to change over directly into the operation of theventilator with assisted cardiopulmonary resuscitation (CPR) from anyother operation of the ventilator, for example, a pressure-controlled orvolume-controlled operation without assisted cardiopulmonaryresuscitation (CPR), as well as directly into another operation from theoperation of the ventilator with assisted cardiopulmonary resuscitation(CPR).

Such a control element or switching element is preferably designed as apart of the input unit, and such a control element is more preferablyarranged on the front side in the direct working range and range ofaccess of the user.

In another preferred embodiment of the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR), the operation of theventilator with assisted cardiopulmonary resuscitation (CPR) is switchedon and/or off by an external signal. The external signal is preferablyconnected electrically, optically or telemetrically to the ventilator bymeans of the data interchange.

In an especially preferred embodiment of the method for operating aventilator which assists cardiopulmonary resuscitation (CPR), at leastone physiological signal is analyzed as a parameter relevant for thecardiopulmonary resuscitation (CPR). Such relevant parameters arepreferably a current oxygen saturation (SPO₂) in the patient's blood, anoxygen concentration (O₂) in the lungs or in the air exhaled by thepatient or a carbon dioxide concentration (CO₂) in the air exhaled bythe patient.

In a preferred embodiment variant of this especially preferredembodiment (HG1), the method for operating a ventilator which assistscardiopulmonary resuscitation (CPR) is designed to determine a qualityindex (QIndex-CM) for the performance of the cardiac massage (CM) fromthe at least one physiological signal. The quality index (QIndex-CM) ispreferably determined by means of a comparison of the signal of the atleast one physiological signal with a predetermined comparison value orfrom the fact that a predetermined threshold value is exceeded or notreached.

In another variant of this especially preferred embodiment (HG2) of themethod for operating a ventilator which assists cardiopulmonaryresuscitation (CPR), the at least one physiological signal is analyzedto automatically start and/or end the operation of the ventilator withassisted cardiopulmonary resuscitation (CPR).

In a special variant of this especially preferred embodiment (HG3) ofthe method for operating a ventilator which assists cardiopulmonaryresuscitation (CPR), a ventilation pressure and/or a time curve of theventilation pressure are analyzed to recognize a cardiac massage (CM)currently being applied and to automatically start the operation of theventilator with assisted cardiopulmonary resuscitation (CPR).

In another preferred embodiment of the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR), the alarm generationof the ventilator is also preferably adapted to the effect of thecardiac massage (CM) on the ventilation by means of a human-machineinterface (user interface).

The measured values detected by the ventilator and values derived fromthe measured values, as well as the target values of the ventilationitself, are influenced, changed and partially even distorted, at leastfrom time to time, by the cardiac massage (CM) in such a way that areliable alarming of the user concerning the quality of the ventilationis not possible during the application of the cardiac massage (CM).

The essential values detected by measurement and measured variables ofventilation derived from measured values include:

-   -   Ventilation pressure (P) and its time curve, gradients of the        ventilation pressure (ΔP/Δt), and volume flow (ΔV/Δt).

Derived measured variables and measured values are, for example,respiratory minute volume (MV), minute volume of carbon dioxide (MVCO₂),cardiac output (cardiac minute volume).

The following essential target values may be mentioned as examplesduring ventilation: tidal volume (Vt), respiration rate (RR), meanventilation pressure. This list of the measured values and measuredvariables is not comprehensive here, and additional parameters based onphysical measured variables for regulating and controlling theventilation, as well as measured values and measured variables used forthe monitoring of ventilation and the patient being ventilated are alsocovered in the sense of the present invention. These mentioned valuesare monitored during the controlled mechanical ventilation to determinewhether they do not leave a predetermined range (tolerance range) thatis safe for the patient, e.g., whether they do not exceed an upper alarmlimit, and whether they do not fall below a lower alarm limit, orwhether they are located, with a preset variation, around preset valuesor around a preset curve of the values during a preset time course ortime interval. Suitable methods for monitoring the values are thresholdvalue and tolerance monitoring, signal gradient monitoring (Δx/Δt),signal shape and tolerance comparisons, for both individual discretemeasured values, time-averaged or filtered measured values or measuredvalue and signal curves. In particular, the pressure measurement isaffected very massively by the compression applied to the chest by thecardiac massage (CM). The alarm generation for the user thereforeincludes an alarm and signal evaluation specially adapted to the methodfor operating a ventilator which assists cardiopulmonary resuscitation(CPR) or precedes the alarm generation in this embodiment of the methodfor operating a ventilator which assists cardiopulmonary resuscitation(CPR). The alarm generation for the user takes place typically opticallyby signaling on a display screen or display, as well as often alsoadditionally acoustically, e.g., by activating a sound-generatingelement, for example, a horn or a loudspeaker. The alarm and signalevaluation is adapted to the cardiopulmonary resuscitation (CPR) and thecardiac massage (CM) in such a way that specifications or the alarmlimits of the measured values affected by the cardiac massage (CM) areraised in case of an upper alarm limit and lowered in case of a loweralarm limit, so that a tolerance range of alarm generation is expandedin its limits upwardly and downwardly, and the original alarm limits setare preferably maintained in a form of intermediate alarm stages.

In a special variant, provisions are made in the method for operating aventilator which assists cardiopulmonary resuscitation (CPR) for analarm or at least a signal generation to be delayed in time or to bepartially or completely skipped for at least one measured value or atleast one measured variable or an event. In another special variant,provisions are made in the method for operating a ventilator whichassists cardiopulmonary resuscitation (CPR) for an acoustic alarm to bepartially or fully skipped for at least one measured value or at leastone measured variable or an event. In another special variant,provisions are made in the method for operating a ventilator whichassists cardiopulmonary resuscitation (CPR) for the acoustic alarm to bedelayed in time for at least one measured value or at least one measuredvariable or an event.

The different embodiments and variants of the embodiments of the methodfor operating a ventilator which assists cardiopulmonary resuscitation(CPR), and of a device designed as a ventilator for mechanicalventilation, which assists cardiopulmonary resuscitation (CPR), whichare mentioned in the present application, represent, on the one hand,independent inventive means for accomplishing the object of the presentinvention, and any possibility of combination of the differentembodiments and variants of the embodiments with one another leads to animprovement of the function of the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR) or of the devicedesigned as a ventilator, and they are likewise covered by theembodiments described and shown as well in the sense of the presentinvention.

One embodiment of a medical system comprises a ventilator with aninspiratory metering unit to assist cardiopulmonary resuscitation (CPR),with an expiratory metering unit, with a control and regulation unit,with an alarm and alarm adaptation unit for monitoring threshold valuesand tolerance ranges, with a display, signal generation and operatingunit for outputting display values, alarms and signals for a user andfor inputting setting values by a user, with at least one pressuresensor, with at least one additional sensor, with a sensor and datainterface, and with a tube system for the air-carrying connection of theventilator to a patient. The medical system comprises, furthermore, atleast one physiological monitoring device connected to the ventilatorvia the sensor and data interface of the ventilator for the transmissionof data.

The physiological monitoring device is preferably designed as acapnometer or an oximeter/capnometer. The capnometer oroximeter/capnometer is also preferably designed to detect a carbondioxide concentration (CO₂) and/or an oxygen concentration (O₂) in theair exhaled by a patient and to transmit it to the ventilator via thesensor and data interface. The alarm and alarm adaptation unit isdesigned, together with the display and signal generation unit and thecontrol and regulation unit, to change at least one alarm generation onthe ventilator. Furthermore, the alarm and alarm adaptation unit isdesigned, together with the display and signal generation unit, thecontrol and regulation unit and the sensor and data interface, to changeat least one alarm generation on the physiological monitoring device.Alarm generation or alarm generation at the ventilator and/or at the atleast one physiological monitoring device is defined in the sense of thepresent invention such that an alarm signal is sent optically oracoustically, optically and acoustically simultaneously or offset intime, and/or that a further or additional external signaling takes placedue to the alarm being available in the form of an electric signal at ananalog or digital, wired or telemetric data interface. The changes inthe alarm generation at the ventilator and/or the change in the alarmgeneration at the physiological monitoring device preferably cause thatthose physiological signals that are used by the ventilator to carry outthe operation for assisting the cardiopulmonary resuscitation (CPR) areno longer taken into account by the alarm generation at thephysiological monitoring device, but those physiological signals thatare used by the ventilator to carry out the operation for assistingcardiopulmonary resuscitation (CPR) are taken into account only by thealarm generation of the ventilator. This advantageously leads to theavoidance of multiple alarms in connection with essentially identicalcauses of alarm and thus relieves the user during the operation andhandling of the physiological monitoring device and the ventilatorduring the operation of the ventilator for assisting cardiopulmonaryresuscitation (CPR).

Another embodiment of a medical system comprises a ventilator with aninspiratory metering unit for assisting cardiopulmonary resuscitation(CPR), with an expiratory metering unit, with a control and regulationunit, with an alarm and alarm adaptation unit for monitoring thresholdvalues and tolerance ranges, with a display, signal generation andoperating unit for outputting display values, alarms and signals for auser and for inputting setting values by a user, with at least onepressure sensor, with at least one additional sensor, with a sensor anddata interface, and with a tube system for the air-carrying connectionof the ventilator to a patient.

The further embodiment of the medical system comprises, furthermore, anassist device for the automatic performance of cardiac massage (CM) onthe chest of patient. The assist device is designed to perform cardiacmassage (CM) on the chest of the patient by means of an elementadjustable preferably by means of a motor, electric motor,electromechanically, mechanically, hydraulically or pneumatically,preferably in the form of a chest belt or a holder suitably arranged onthe chest. The assist device is connected to the ventilator for datatransmission by means of the sensor and data interface. The assistdevice is able by means of a data transmission to make statusinformation available for the ventilator concerning the currentperformance of a cardiac massage (CM). The medical system is designed tostart or end the operation of the ventilator which assistscardiopulmonary resuscitation (CPR) or to bring the ventilator into atemporary state of pause by means of the status information concerningthe current performance of cardiac massage (CM).

Synchronization is made possible in this way between the ventilator,which assists cardiopulmonary resuscitation (CPR), and the assistdevice. A volume and/or a pressure in the patient's lungs can be adaptedto the cardiac massage (CM) such that, on the one hand, the pressure andthe volume are higher during a compression by the assist device at theend of the inspiration and before the start of expiration than thepressure and volume that would fill the patient's lungs at the end ofthe inspiration in case of the application of ventilation with a normalmode of ventilation, i.e., a mode of ventilation without assistedcardiopulmonary resuscitation (CPR). As such the lungs fill part of thechest cavity and thus the heart has reduced possibility to yield in thechest cavity during a compression by the cardiac massage (CM). On theother hand, the pressure and the volume levels during a decompression,by the assist device, at the end of the expiration and before the startof the inspiration by the patient, is such that the lungs are filledessentially only with a volume. The residual volume, that is reducedcompared to ventilation with a normal mode of ventilation, withoutassisted cardiopulmonary resuscitation (CPR), remains in the lungs, sothat a backflow of blood from the body to the heart is assisted during adecompression of the chest cavity.

In another preferred manner, the ventilator in the medical system isdesigned by means of the data transmission to bring the assist devicetemporarily into a state of pause. This makes it possible for ameasurement of pressure and/or flow to be possible at the ventilatorwithout the effect of the assist device, especially in phases with aventilation situation that is difficult and possible life-threateningfor the patient.

Another embodiment of a medical system comprises a ventilator with aninspiratory metering unit for assisting cardiopulmonary resuscitation(CPR), with an expiratory metering unit, with a control and regulationunit, with an alarm and alarm adaptation unit for monitoring thresholdvalues and tolerance ranges, with a display, signal generation andoperating unit for outputting display values, alarms and signals to auser, and for inputting setting values by a user, with at least onepressure sensor, with at least one additional sensor, with a sensor anddata interface, and with a tube system for the air-carrying connectionof the ventilator to a patient.

Furthermore, the medical system comprises a voltage generator forresuscitating the cardiovascular function, preferably a defibrillator.The voltage generator for resuscitating the cardiovascular system or thedefibrillator is designed to introduce an electric voltage pulse intothe upper body of a patient via at least two electrodes placed on theskin of the chest of a patient and thus to stimulate the cardiovascularfunction of the patient to resume its independent function. The voltagegenerator/defibrillator is connected by means of the sensor and datainterface of the ventilator for data transmission. The voltagegenerator/defibrillator is able by means of the data transmission tosend a pause signal to the ventilator during the operation of aventilator which assists cardiopulmonary resuscitation (CPR), especiallypreferably during phases during which electric voltage pulses areintroduced, and to bring the ventilator temporarily into a state ofpause. The ventilator stops the ventilation operation in the state ofpause during the operation of a ventilator which assists cardiopulmonaryresuscitation (CPR) in such a form that inspiratory ventilation strokesare no longer performed, but only the pressure sensor system andpreferably additional sensor systems continue to operate, and theventilator is kept in a standby until the state of pause is ended by thevoltage generator/defibrillator via the data transmission. The medicalsystem is designed to bring the ventilator temporarily into a state ofpause during the operation of a ventilator which assists cardiopulmonaryresuscitation (CPR).

It is preferably made possible in the above-mentioned variants of themedical system by means of the data transmission via the sensor and datainterface, preferably by means of control signals exchanged in themedical system, to change an alarm generation on the ventilator and/oron the physiological monitoring device and/or on the voltage generatorfor resuscitating the cardiovascular function and/or on the assistdevice for the automatic performance of cardiac massage (CM) in such away that an alarm, at least a signal generation, is delayed in timeand/or partially or completely skipped and/or an acoustic alarm ispartially or fully skipped or delayed in time for at least one measuredvalue or for at least one measured variable and/or for at least oneevent, and/or to vary the volume of at least one alarm for the at leastone measured value or for the at least one measured variable or for theat least one event.

The alarm generation is changed in another preferred manner in such away that alarm limits are raised on the basis of originally set alarmlimits in case of an upper alarm limit and/or alarm limits are loweredon the basis of originally set alarm limits in case of a lower alarmlimit. This preferably leads to an expansion of a tolerance range foralarming.

Some exemplary embodiments of the present invention are shown in thefigures and will be explained in more detail below. The various featuresof novelty which characterize the invention are pointed out withparticularity in the claims annexed to and forming a part of thisdisclosure. For a better understanding of the invention, its operatingadvantages and specific objects attained by its uses, reference is madeto the accompanying drawings and descriptive matter in which preferredembodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1a is a schematic overview of a ventilator;

FIG. 1b is a schematic overview of an emergency ventilator;

FIG. 2 is a schematic diagram of a ventilation control according toFigures la and lb;

FIG. 3 is a diagram of concentration ranges of the CO₂ concentration;

FIG. 4 is a schematic sequence of the method for operating a ventilatorwhich assists cardiopulmonary resuscitation (CPR);

FIG. 5a is a diagram showing time graphs of the ventilation pressure,cardiac massage (CM) and CO₂ measurement;

FIG. 5b is a diagram showing time curves of the ventilation pressure,cardiac massage (CM) and CO₂ measurement, chronologically following thetime curve of FIG. 5a ;

FIG. 5c is a diagram showing time curves of the ventilation pressure,cardiac massage (CM) and CO₂ measurement, chronologically following thetime curve of FIG. 5b ;

FIG. 5d is a diagram showing time curves of the ventilation pressure,cardiac massage (CM) and CO₂ measurement, chronologically following thetime curve of FIG. 5c ;

FIG. 5e is a diagram showing time curves of the ventilation pressure,cardiac massage (CM) and CO₂ measurement, chronologically following thetime curve of FIG. 5d ;

FIG. 6 is a diagram of the time course of ventilation during theoperation of a ventilator with and without assisted cardiopulmonaryresuscitation (CPR);

FIG. 7a is a schematic overview of a medical system with a ventilatoraccording to FIG. 1a or FIG. 1b and with an assist device for theautomatic performance of cardiac massage (CM); and

FIG. 7b is a schematic overview of a medical system with a ventilatoraccording to FIG. 1a or FIG. 1b and with a voltage generator suitablefor resuscitation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1a shows a first schematic overview of the components of aventilator 1, which is equipped for performing ventilation. Theventilator 1 has the following components:

An inspiration valve 2, an expiration valve 3, a display and signalgeneration unit 4, an input unit 5, a control and regulation unit 7, avoltage supply unit 8, a gas-mixing and metering unit 9 with aventilation drive designed as a blower unit 27 and with anoxygen-air-mixing and metering valve 29, and air-gas supply unit 95 andan oxygen gas supply unit 96, a flow-measuring unit 11, a pressure- andflow-regulating unit 12, an expiratory pressure-measuring unit 13, aninspiratory pressure-measuring unit 23, a pressurized oxygen cylinder 14with a pressure-reducing unit 15, an inspiratory gas port 91, anexpiratory gas port 92, and a gas outlet 93. Furthermore, a manipulatedvariable input 6 is present, by means of which manipulated variables 16relevant for ventilation, such as respiration rate (RR), pressureamplitude ( P_(amplitude)), mean positive target pressure (P) ofventilation, tidal volume (V_(T)), I:E ratio (Ratio_(I:F)) of the inputunit 5, reach the control and regulation unit 7 and are transmitted tothe pressure- and flow-regulating unit 12 from there. These manipulatedvariables 16 are used as preset desired values for the start and for theperformance of the ventilation. The patient 47 is connected to theventilator 1 by means of a connection piece (Y-piece) 17 via aninspiratory gas port 91 and an expiratory gas port 92 by means of twosupply lines 48, via a two-tube system in this case shown in FIG. 1a .The exhaled air escapes via the gas port 93 from the ventilator 1 intothe surrounding area. An acoustic signal device 44, designed, forexample, in the form of a horn or a loudspeaker, as well as an opticalsignal device 45, designed, for example, as a lamp, an LED or anotheroptical display element, are contained in the display and signalgeneration unit 4. The input unit 5 may be designed such that it iscombined with the display and signal generation unit 4 in a userinterface 54, and one or more control elements 55, designed, forexample, as key or switching elements or as a keyboard, may also beadditionally integrated. The control elements 55 are designed in thepresent invention to start the method with assisted cardiopulmonaryresuscitation (CPR) on the ventilator 1, to control it in interactionwith the control and regulation unit 7 and to configure or end it.Furthermore, a data interface 30 is provided on the ventilator 1.Additional sensor systems or accessories may be directly connected viathis data interface 30 to the ventilator 1 with a unidirectional orbidirectional data exchange, or a unidirectional or bidirectionalexchange of data 21 from the ventilator 1 with external devices may beperformed. This FIG. 1a shows as an external physiological sensor a “CO₂sidestream sensor” 31, which draws breathing air from the connectionpiece (Y-piece) 17 by means of a suction line 32 and analyzes it withrespect to the carbon dioxide concentration, and is connected to thedata interface 30.

FIG. 1b shows a second schematic overview of the components of anemergency ventilator 1′, which is equipped for performing emergencyventilation. Identical components in Figures la and lb are designated bythe same reference numbers. The emergency ventilator 1′ has thefollowing components:

An inspiration valve 2, an expiration valve 3, a display and signalgeneration unit 4, an input unit 5, a control and regulation unit 7, avoltage supply unit 8, a gas-mixing and metering unit 9 with an ejector94, an air-gas supply unit 95 and an oxygen gas supply unit 96, aflow-measuring unit 11, a pressure- and flow-regulating unit 12, anexpiratory pressure-measuring unit 13′, an inspiratorypressure-measuring unit 23, a pressurized oxygen cylinder 14 with apressure-reducing unit 15, and an inspiratory gas port 91. Furthermore,a manipulated variable input 6 is present, by means of which manipulatedvariables 16 relevant for ventilation, such as respiration rate (RR),pressure amplitude (P_(amplitude)), mean positive target pressure (P) ofthe ventilation, tidal volume (V_(T)), I:E ratio (Ratio_(I:E)), reachthe control and regulation unit 7 from the input unit 5 and aretransmitted from there to the pressure- and flow-regulating unit 12.These manipulated variables 16 are used as desired specifications forthe start and for the performance of the emergency ventilation. Thepatient 47 is connected to the emergency ventilator 1 by means of aconnection piece (Y-piece) 17 via an inspiratory gas port 91 by means ofa supply line 48′, in this case shown in this FIG. 1b via a one-tubesystem. The exhaled air escapes via a gas outlet 93′ directly at theconnection piece 17 into the surrounding area. An acoustic signal device44, designed, for example, in the form of a horn or a loudspeaker, aswell as an optical signal device 45, designed for example, as a lamp, anLED or another optical display element, are contained in the display andsignal generation unit 4. The input unit 5 may be designed such that itis combined with the display and signal generation unit 4 in a userinterface 54, and one or more control elements 55, designed, forexample, as keys or switching elements or as a keyboard, may also beadditionally integrated. The control elements 55 are designed in thepresent invention to start the method with assisted cardiopulmonaryresuscitation (CPR) on the emergency ventilator 1′, to control the CPRin interaction with the control and regulation unit 7 and to configureor end it. Furthermore, an interface is provided for electric energy 90.A rechargeable battery pack 88, which can be supplied with electricenergy and charged from the outside by means of an energy-charging andsupply element 89 and via the interface for electric energy 90, isconnected to the voltage supply unit 8. Furthermore, a data interface 30is provided on the emergency ventilator 1′. Additional sensors oradditional devices may be connected directly via this data interface 30to the emergency ventilator 1′ with a unidirectional or bidirectionaldata exchange, or data 21 of external devices can be exchangedunidirectionally or bidirectionally with the emergency ventilator 1′ viathe data interface 30.

A physiological sensor 31′ designed as a “CO₂ mainstream sensor” fordetermining a carbon dioxide concentration (CO₂) in the breathing gas ofthe patient 47 and a flow sensor 24 located close to the patient fordetermining the flow rates to and from the patient 43 at the connectionpiece (Y-piece) 17 are connected as additional sensors to the emergencyventilator 1′ in this FIG. 1b . The physiological sensor 31′ and theflow sensor 24 located close to the patient transmit measured values toa corresponding CO₂ analyzer 37 by means of data lines 36. Thecorresponding analyzer 37 further transmits the measured values via thedata interface 30 to the emergency ventilator 1′. The arrangement of the“CO₂ mainstream sensor” 31′ and of the flow sensor 24 located close tothe patient at the connection piece in the proximity of each other inspace is especially advantageous for forming a variable derived from themeasured values of these two sensors, a “minute volume of carbondioxide,” MVCO₂. This minute volume CO₂ (MVCO₂) can advantageously beused to assess the quality of a cardiac massage (CM) being performed inthe device for assisting cardiopulmonary resuscitation (CPR) as well asin the method for assisting cardiopulmonary resuscitation (CPR). As isshown in more detail in FIGS. 7a and 7b , additional external devices,for example, a voltage generator for resuscitating the cardiovascularfunction (defibrillator) or an assist device for automaticallyperforming a cardiac massage (CM) can be connected to the ventilator 1(FIG. 1a ) via the data interface 30, so that, on the one hand,information and/or data from the external device, for example, ECGsignals of the defibrillator, and, on the other hand, also informationfrom the ventilator 1, 1′ to the external device for controlling thelatter, for example, start/stop/pause signals, can be exchanged in orderto assist the device for assisting cardiopulmonary resuscitation (CPR)and to also include it in the method for assisting cardiopulmonaryresuscitation (CPR).

FIG. 1b schematically shows a variant of a medical system 1490 with theventilator 1′ combined with the CO₂ analyzer 37 connected via the sensorand data interface 30 and with the carbon dioxide sensor 31′ connectedby means of data line 36 as a physiological sensor.

Another, and essentially similar medical system is obtained according toFIG. 1a with the ventilator 1 combined with the physiological sensor 31connected via the sensor and data interface 30.

In a diagram 10, FIG. 2 shows essential elements of the ventilator 1, 1″according to FIGS. 1a, 1b for the performance of the method foroperating a ventilator which assists cardiopulmonary resuscitation(CPR). Identical elements in FIGS. 1a, 1b are designated by the samereference numbers as in FIG. 2. Corresponding to FIGS. 1a, 1b , theinspiration valve 1, the expiration valve 3, the display and signalgeneration unit 4, the input unit 5, the pressure-measuring unit 13, theflow-measuring unit 11, the control and regulation unit 7 with thepressure- and flow-regulating unit 12 and with the manipulated variableinput 6 for the input variables 16, the data interface 30 for data 21,and the device 31 designed as a CO₂ sensor, which is in air-carryingconnection with the patient 47 via the suction line 32 and theconnection piece 17, are shown. The patient is connected to theventilator 1, 1′ (FIGS. 1a, 1b ) via the inspiratory gas port 91 and theexpiratory gas port 93 and the connection piece. The following elementsare shown in detail for illustration in this diagram 10 in FIG. 2. Anadaptation and time lag element 22 is symbolically arranged upstream ofthe inspiration valve 2 in this diagram 10 in FIG. 2. An adaptation andtime lag element 33 is likewise symbolically arranged upstream of theexpiration valve 3 in this diagram 10. The adaptation and time lagelements 22, 33 are preferably embodied technically as components of thecontrol and regulation unit 7. The inspiratory time lag element 22 andthe expiratory time lag element 33 are actuated by the control andregulation unit 7 and activated during the operation of the ventilator1, 1′ (FIGS. 1a, 1b ) with assisted cardiopulmonary resuscitation (CPR)in such a way that the regulation of the ventilation does not responddirectly to any changes in the measured ventilation pressure.Furthermore, the expiratory time lag element 33 is actuated by thecontrol and regulation unit 7 such that the start of the expirationphase is delayed during the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR). Furthermore, the inspiratory timelag element 22 is actuated by the control and regulation unit 7 suchthat the start of the inspiration phase is delayed during the operationof the ventilator with assisted cardiopulmonary resuscitation (CPR).Furthermore, this diagram 10 shows that an alarm and alarm adaptationunit 46 is inserted between the control and regulation unit 7 and thedisplay and signal generation unit 4.

The alarm and alarm adaptation unit 46 is preferably designed in onetechnical implementation as a part of the control and regulation unit 7or of the display and signal generation unit 4 or as part of theoperating system of the ventilator 1 (FIG. 1a, 1b ). A symbolicinterference variable Z 34 is shown, which represents the effect of thecardiac massage (CM) in the form of pressure changes dP 35 on thepressure measurement 13 as well as indirectly also on the flowmeasurement 11. The pressure variation effect on the signal of theventilation pressure P 610 (FIGS. 5a through 5e ), which is caused bythe cardiac massage (CM), becomes clear especially in the diagramsaccording to FIGS. 5c . The adaptation and time lag elements 22, 33 areused in the method for operating a ventilator for assistingcardiopulmonary resuscitation (CPR) to delay the start of theinspiration phase and the start of the expiration phase in order toassist the cardiac massage (CM). The assist takes place in theexpiration phase by the delay caused by the expiratory time lag element33 bringing about an increase in the initial expiratory pressure leveland hence an increase in an air-filled volume of the patient's lungs, sothat the lungs will fill a part of the chest cavity and the heart willthus have a reduced possibility to yield in the chest cavity during acompression by the cardiac massage (CM). The assist takes place duringthe inspiration phase by the delay caused by the inspiratory time lagelement 22 leading to a reduction of an initial inspiratory pressurelevel in the patient's lungs and generating a slight vacuum in the lungsin relation to the ambient pressure by a supply of fresh breathing airat the start of the inspiration phase being delayed in time by a delaywith which the inspiration valve 2 opens. The pressure in the chestcavity is thus reduced during the performance of the method foroperating a ventilator for assisting cardiopulmonary resuscitation(CPR), so that the backflow of the blood from the body to the heartduring the decompression of the chest cavity is assisted. The alarm andalarm adaptation unit 46 is used in the method for operating aventilator for assisting cardiopulmonary resuscitation (CPR), so thatalarms that would be triggered by the cardiac massage (CM) due to theinterference variable Z 34, e.g., as pressure changes dP 35, which issuperimposed to the signal of the ventilation pressure, which lattersignal is caused by the ventilation, are treated such that the alarmgeneration to the user is partially, temporarily or fully suppressed forthe duration during which the method for operating a ventilator withassisted cardiopulmonary resuscitation (CPR) is being carried out. Theinterference variable may also be filtered in respect to its amplitudeor duration.

FIG. 3 shows how a predetermined first threshold value 650 and apredetermined second threshold value 660 of the CO₂ concentration dividethe diagram of a CO₂ concentration 506 into three concentration ranges645, 655, 665. The CO₂ concentration is shown in the unit mmHg on theordinate 670, and the time course is plotted in a dimensionless form onthe abscissa 680.

A first concentration 645 is obtained, in which the CO₂ concentration isbelow the first predetermined threshold value 650. The fact that thisfirst predetermined threshold value 650 is not reached indicates thatthe cardiac massage (CM) is not being performed in a sufficient mannerto maintain the patient's cardiovascular function. There is a secondconcentration range 655, in which the CO₂ concentration is above thefirst predetermined threshold value 650 and below the secondpredetermined threshold value 660. The fact that the secondpredetermined threshold value 660 is not reached indicates that thepatient is not able to maintain his cardiovascular function on his ownand cardiac massage (CM) should therefore be applied by the user. Thereis a third concentration range 665, in which the CO₂ concentration isabove the second predetermined threshold value 660. The fact that thesecond predetermined threshold value is exceeded indicates that thepatient is able on his own to maintain his cardiovascular function andno cardiac massage (CM) is therefore necessary, as well as that acardiac massage (CM) currently being applied by the user should beended. A first predetermined threshold value 650 of 10 mmHg with avariation of +/−2 mmHg and a second predetermined threshold value 660 of40 mmHg with a variation of +/−2 mmHg are suitable values for thepractical use of the ventilator 1, 1′ (FIG. 1a , FIG. 1b ) with assistedcardiopulmonary resuscitation (CPR) in emergency medicine. When the firspredetermined threshold value 650 and the second predetermined thresholdvalue 660 are not reached and exceeded, further and additional criteriamay be used and linked with one another for triggering the messages(FIG. 4) for the user for starting the operation of ventilation withassisted cardiopulmonary resuscitation (CPR) and for regulating (FIG. 2)the ventilation pressure (FIG. 2) during the operation of the ventilatorwith assisted cardiopulmonary resuscitation (CPR).

Such further and additional criteria are, for example, measured valuesand/or setting parameters of the ventilator or measured values and/orsetting parameters of a physiological monitor. An oxygen concentrationis mentioned as an example of setting parameters of a ventilator.

An oxygen partial pressure SPO₂ in the blood or a non-invasivelydetected blood pressure (NBP) or a heart rate (HR) of the patient arementioned as examples of measured values of a physiological monitor,besides the CO₂ concentration.

FIG. 4 shows a schematic sequence 1000 with the start and end of themethod for operating a ventilator for assisting cardiopulmonaryresuscitation (CPR). The sequence 1000 is divided into a time course ofthe ventilation of a patient 47 (FIGS. 1a, 1b , 2) with any desired,originally selected ventilation mode 300, in which no cardiac massage(CM) is being performed on the patient 47 (FIG. 1, 2).

A start 400 of the method for operating the ventilator 1, 1′ (FIGS. 1a,1b ) with assisted cardiopulmonary resuscitation (CPR) is triggered by afirst user interaction 1101 from any desired ventilation mode 300. Theventilation of any desired mode 300 may be a pressure- orvolume-controlled ventilation mode. A physiological sensor or anexternal monitoring device 31, 31′ (FIGS. 1a, 1b ) provides in thedesired ventilation mode 300 current measured signals 600′ of a currentcarbon dioxide concentration, as well as measured signals 601, 602, 603,604, 605 of a current carbon dioxide concentration are provided in themethod for operating the ventilator 1, 1′ (FIGS. 1a, 1b ) with assistedcardiopulmonary resuscitation (CPR) in a continuously repeating sequence600 at predetermined time intervals as input variables for the sequence1000 of the method for operating the ventilator 1 (FIG. 1a, 1b ) withassisted cardiopulmonary resuscitation (CPR). The start 400 of themethod for operating the ventilator 1, 1′ (FIGS. 1a, 1b ) with assistedcardiopulmonary resuscitation (CPR) may take place by the first userinteraction 1101 or else even automatically by the ventilator 1, 1′(FIGS. 1a, 1b ), e.g., on the basis of the measured signals 600′ of thecurrent carbon dioxide concentration, without a user interaction. As analternative, a start 400′ may also take place semi-automatically by theventilator 1, 1′ (FIGS. 1a, 1b ), e.g., on the basis of the measuredsignals 600′ of the current carbon dioxide concentration, the start 400′being suggested by the ventilator 1 (FIG. 1a, 1b ) via the combineddisplay, signal generation and input unit 54 (FIGS. 1a, 1b ), and thestart 400′ is then finally acknowledged by a first user interaction1101′, and the ventilator 1, 1′ (FIGS. 1a, 1b ) will then change over tothe operation of the ventilator 1, 1′ (FIGS. 1a, 1b ) with assistedcardiopulmonary resuscitation (CPR) 1000. The measured signals 601, 602,603, 604, 605 of the current carbon dioxide concentration, which aredetected continuously in the sequence 600, are evaluated in the sequence1000. The relation of the carbon dioxide concentration to the firstpredetermined threshold value 650 and the relation of the carbon dioxideconcentration to the second predetermined threshold value 660 arechecked by a comparison in this analysis in the sequence 1000. As anexample, the sequence 1000 is divided in this FIG. 4 into phases 1001,1002, 1003, 1004, 1005, in which the current carbon dioxideconcentration is compared with the first predetermined threshold value650 and with the second predetermined threshold value 660. The timing ofthe phases 1001, 1002, 1003, 1004, 1005 in the sequence may follow eachother, as is shown in FIG. 4, but the present invention also covers thecase in which the phases 1001, 1002, 1003, 1004, 1005 may occur withouta chronological coordination or coordinated with one another at anydesired time during the ventilation or in the course of the ventilationduring the treatment or emergency treatment of a patient. The durationin time of the individual phases 1001, 1002, 1003, 1004, 1005 depends inthis case on the treatment situation, the patient's constitution and theassessment made by the user in this regard. Furthermore, the duration intime of the individual phases 1001, 1002, 1003, 1004, 1005 indirectlydepends on the selection of the first predetermined threshold value 650and of the second predetermined threshold value 660, as well as on therelation of the threshold values 650, 660 to one another. In the firstphase 1001 of the sequence 1000, the comparison shows that the currentcarbon dioxide concentration 601 is above the first predeterminedthreshold value 650 and below the second predetermined threshold value660 and is thus in a second concentration range of the CO₂ concentration655 (FIG. 3). This is evaluated as an indication that the cardiovascularsituation is being carried out successfully for supplying the organswith oxygen by means of the cardiac massage (CM). In the second phase1002 of the sequence 1000, the comparison shows that the current carbondioxide concentration 602 is below the first predetermined thresholdvalue 650 and below the second predetermined threshold value 660 and itis thus in a first concentration range of the CO₂ concentration 645(FIG. 3). This is evaluated as an indicator that the cardiac massage(CM) is not being performed in a sufficient manner to replace thepatient's cardiovascular function and to supply the vital organs,especially the brain, with a sufficient amount of oxygen. A firstmessage 701 is sent to the user that the cardiac massage (CM) is notbeing performed properly. In the third phase 1003 of the sequence 1000,the comparison shows that the current carbon dioxide concentration 603is again above the first predetermined threshold value 650 and below thesecond predetermined threshold value 660 and is consequently in a secondconcentration range of the CO₂ concentration 655 (FIG. 3). This isevaluated as an indication that the cardiovascular function is againbeing performed successfully for supplying the organs with oxygen bymeans of the cardiac massage (CM). A second message 702 is sent to theuser that the cardiac massage (CM) is again being performed properly.The comparison shows, in the fourth phase 1004 of the sequence 1000,that the current carbon dioxide concentration 604 continues to be abovethe first predetermined threshold value 650 and below the secondpredetermined threshold value 660. The comparison shows in the fifthphase 1005 of the sequence 1000 that the current carbon dioxideconcentration 605 is above the first predetermined threshold value 650and above the second predetermined threshold value 660 and is thus in athird concentration range of the CO₂ concentration 665 (FIG. 3). This isevaluated as an indication that the cardiovascular function with thesupply of the organs with oxygen is again maintained by the patientindependently. A third message 703 is sent to the user that thecardiovascular function of the patient can again be maintainedindependently. The fifth phase 1005 of the sequence thus passes over,for example, in this FIG. 4, to the ending 500 of the method foroperating the ventilator 1, 1′ (FIGS. 1a, 1b ) with assistedcardiopulmonary resuscitation (CPR). An ending 500 of the method foroperating the ventilator 1, 1′ (FIGS. 1a, 1b ) with assistedcardiopulmonary resuscitation (CPR) is triggered by a second userinteraction 1102 in this FIG. 4. The ventilation of the patient 47(FIGS. 1, 2) is then continued with any desired, originally selectedventilation mode 300 or with any other desired ventilation mode 300′.The any desired ventilation mode 300, 300′ may be a pressure- orvolume-controlled ventilation mode. However, the ending 500 may also bebrought about automatically by the ventilator 1 (FIGS. 1a, 1b ) withouta user interaction, or an ending 500′ may also be brought aboutsemi-automatically by the ventilator 1, 1′ (FIGS. 1a, 1b ), in whichcase the ending 500 is suggested by the ventilator 1, 1′ (FIGS. 1a, 1b )via the combined display, signal generation and input unit 54 (FIGS. 1a,1b ), and the ending 500′ is finally acknowledged by a user interaction1102′, and the ventilator 1, 1′ (FIGS. 1a, 1b ) will then switch over tothe any desired ventilation mode 300, 300′.

FIGS. 5a through 5e show exemplary diagrams 501, 502, 503, 504, 505 ofthe time courses of a mechanical ventilation of a patient with a cardiacmassage (CM) being performed simultaneously.

FIGS. 5a through 5e have an abscissa 640 and three ordinates 630, whichcoordinate system shows, synchronously in time and horizontally oneabove another, the time courses of a ventilation pressure P 610 of thepatient. These are diagrams illustrating whether a cardiac massage (CM)is being applied, which is designated as a so-called CM activity 615 inthe present invention, as well as a CO₂ concentration cCO₂ 620.

The ventilation pressure P 610 of the patient is usually measured andscaled, in medical practice, in the dimensions mmH₂O or mbar or hPa. TheCM activity 615 is dimensionless. The CO₂ concentration cCO₂ 620 isusually measured and scaled, in medical practice, in the dimension mmHgThese are shown for different phases of a typical emergency ventilationsituation.

The curves 610, 620 and their chronological assignment to one anothercorrespond in FIGS. 5a through 5e , in principle, to a conversion with a“CO₂ sidestream sensor” 31 (FIG. 1a ). The chronological assignment isshown only as an example in FIGS. 5a through 5e , because a plurality ofmarginal conditions, for example, the length of the supply lines 48, 48′(FIGS. 1a, 1b ), the length and diameter of the suction line 32 (FIG. 1a), the time characteristic of the components involved and of the signalprocessing, play an essential role in practice. A fundamentallydifferent chronological assignment, which would be improved in terms ofthe chronological synchronicity of the curves 610, 620, becausedifferent marginal conditions would now become noticeable, would beobtained when using a “CO₂ mainstream sensor” 31 (FIG. 1b ).

FIGS. 5a through 5a are explained in more detail with a jointdescription of the Figures. A typical sequence of events in an emergencysituation of a patient being ventilated, with the need for and theapplication of a temporary cardiac massage (CM) or cardiopulmonaryresuscitation, is shown in a simplified manner and schematically in thesignal curves 501, 502, 503, 50-4, 505 of the ventilation pressure 610and of the carbon dioxide concentration 620 along with the effect of thecardiac massage (CM) 615 on the signal curves of the ventilationpressure 610 and of the carbon dioxide concentration 620.

Mechanical ventilation is assumed in the diagram 501 according to FIG.5a , with the patient intubated or connected to the ventilator 1, 1′(FIGS. 1a, 1b ) via a mask and being ventilated, with a physiologicalmonitoring being connected to detect the patient's vital parameters, theCO₂ concentration 620 being measured as the at least one vitalparameter. Measured values of the physiological monitoring, includingalso the current value of the CO₂ concentration 620, are available tothe ventilator 1, 1′ (FIGS. 1a and 1b ) via a data interface 30 (FIGS.1a, 1b ). The value of the CO₂ concentration 620 is, on average, above afirst predetermined threshold value 650 in the third concentration rangeof the CO₂ concentration 665 (FIG. 3), which indicates that thecardiovascular function of the patient is spontaneous and stable. It isnot necessary to apply cardiac massage (CM) 615, and the ventilator 1,1′ operates in a first mode of operation.

In these exemplary diagrams of the time curves 501, 502, 503, 504, 505of a mechanical ventilation of a patient with cardiac massage (CM) beingperformed simultaneously, FIG. 5b showing the time curve 502 followschronologically the curve 501 of the mechanical ventilation of a patientwithout simultaneously performed cardiac massage (CM) according to FIG.5 a.

In diagram 502 according to FIG. 5b , the CO₂ concentration 620 of thepatient drops at a time T1 in the course of the ventilation below thefirst predetermined threshold value 650 into the first concentrationrange of the CO₂ concentration 645 (FIG. 3). Triggered by the fact thatthe first predetermined threshold value 650 is not reached, theventilator 1, 1′ (FIGS. 1a, 1b ) sends an alarm (FIG. 4) to the user,indicating that the cardiovascular function of the patient is currentlynot given. In addition, a message (FIG. 4) is sent to the user in thefurther time course, indicating that the ventilator has madepreparations for a changeover into the operation of a ventilator withassisted cardiopulmonary resuscitation (CPR), i.e., into the second modeof operation, and is awaiting a final acknowledgement by the user toactivate the operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR) or will automatically perform the changeover intothe operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR). An automatic changeover into the operation of theventilator with assisted cardiopulmonary resuscitation (CPR), i.e., intothe second mode of operation, may be triggered now, for example, by thecircumstance that the first predetermined threshold value 650 of thecarbon dioxide concentration is not reached for a longer time than apredetermined first duration. The ventilator (FIG. 1a, 1b ) will thenchange over into the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR) (second mode of operation)automatically or by an activation initiated by the user, and sends acorresponding message (FIG. 4). The user starts the cardiac massage(CM), and the time curve of the ventilation pressure shows,chronologically after the first time T1 621, the effect of the cardiacmassage (CM) in the form of a superimposition of pressure peaks with thefrequency of the cardiac massage (CM).

In these exemplary diagrams of the time curves 501, 502, 503, 504, 505of the mechanical ventilation of a patient with simultaneously performedcardiac massage (CM) (second mode of operation), FIG. 5c shows the timecurve 503 follows chronologically the curve 502 of the mechanicalventilation of a patient with simultaneously performed cardiac massage(CM) according to FIG. 5 b.

In diagram 503 according to FIG. 5c , the cardiac massage (CM) startedin FIG. 5b persists while the mechanical ventilation is maintained.However, the patient's CO₂ concentration rises to above the firstpredetermined threshold value 650 in the course of the cardiac massage(CM) due to the cardiac massage (CM). However, the patient's CO₂concentration continues to be below the second predetermined thresholdvalue 660 in the second concentration range of the CO₂ concentration 655(FIG. 3), which indicates that the ventilation and the cardiac massage(CM) are being performed in such a way that both the pulmonaryventilation is maintained due to the ventilation and the cardiovascularfunction is maintained for supplying the organs with oxygen by means ofthe cardiac massage (CM), but the patient is still unable toindependently assume and maintain the cardiocirculatory function. Thetime curve of the ventilation pressure 610 shows the effect of thecardiac massage (CM) in the form of a superimposition of pressure peakswith the frequency of the cardiac massage (CM).

In these exemplary diagrams of the time curves 501, 502, 503, 504, 505of the mechanical ventilation of a patient with simultaneously performedcardiac massage (CM), FIG. 5d shows the time curve 504 followschronologically the curve 503 of the mechanical ventilation of a patientwith simultaneously performed cardiac massage (CM) according to FIG. 5c.

The diagram 504 according to FIG. 5d shows the time curve of aventilation with simultaneous cardiac massage (CM), during which the CO₂concentration 620 of the patient is at times below the firstpredetermined threshold value 650 in the first concentration range ofthe CO₂ concentration 645 (FIG. 3). When the first predeterminedthreshold value 650 is not reached at a second time T2 622, theventilator 1, 1′ (FIGS. 1a, 1b ) sends a message (FIG. 4) to the user inthe method of operation of a ventilator 1, 1′ (FIGS. 1a, 1b ),indicating that the cardiac massage (CM) is not being performed in asufficient manner to replace the patient's cardiovascular function andto supply the vital organs, especially the brain, with a sufficientquantity of oxygen. This happens, for example, when the pressure massage(CM) is not being performed with a sufficient pressure or the timeintervals between the individual administrations of the pressure massage(CM) on the chest of the patient are too long or the cardiac massage(CM) as a whole is being performed irregularly. The time curve of theventilation pressure 610 also shows at the second time T2 622 that thecardiac massage (CM) 615 is not being performed properly, because thesuperimposition of pressure peaks with the frequency of the cardiacmassage (CM) is no longer visible. Cardiac massage (CM) 615 is performedagain, as a whole, properly in the further course of this diagram,following chronologically the second time T2 622.

In these exemplary diagrams of the time curves 501, 502, 503, 504, 505of the mechanical ventilation of a patient with simultaneously performedcardiac massage (CM), FIG. 5e showing the time curve 505 that followschronologically the curve 504 of the mechanical ventilation of a patientwith simultaneously performed cardiac massage (CM) according to FIG. 5d.

In the diagram 505 according to FIG. 5e , the time curve shows that theCO₂ concentration rises at a third time T3 623 to above the secondpredetermined threshold value 660 into the third concentration range ofthe CO₂ concentration 665, which indicates that the cardiovascularfunction can again be maintained in a stable form by the patient himselfThe cardiac massage (CM) is ended in the further course at a fourth timeT4 624, chronologically following the third time T3 623. The fact thatthe CO₂ concentration of the patient remains above the secondpredetermined threshold value 660 in the further course following thefourth time T4 624 can be considered to be a further indicator that thepatient can now maintain his cardiovascular function again in a stableform on his own.

In the process 1000 (FIG. 4) of the ventilation with temporaryapplication of cardiac massage (CM) according to FIGS. 5a through 5e ,some alarm limits of the ventilator 1, 1′ (FIGS. 1a, 1b ) are adjustedor faded out by a corresponding adaptation device 46 (FIG. 2). Thisoccurs during the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR) in such a way or the acoustic alarmis preferably “muted,” so that the user is not burdened in a disturbingmanner during the ventilation, during the application of the cardiacmassage (CM) and during the treatment of the patient.

Furthermore, the monitoring of the instances in which the firstpredetermined threshold value 650 is exceeded or not reached and themonitoring of the instances in which the second predetermined thresholdvalue 660 is exceeded or not reached are preferably provided with afiltering, so that the changes into or out of the operation of theventilator with assisted cardiopulmonary resuscitation (CPR) and themessages (FIG. 4) to the user cannot take place excessively frequentlyduring the instances in which the threshold value is exceed or notreached. This filtering may be performed, for example, as amplitudefiltering, mean value filtering or median filtering directly on thevalue of the CO₂ concentration or on values derived therefrom, and atime-based filtering with a monitoring time window is likewise possible.The monitoring time window may be, for example, such that changes in theCO₂ concentration values must last for a certain time before changeoversinto or out of the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR) are performed or messages (FIG. 4)are sent to the user. Besides the adaptation of the output of messages(FIG. 4) during the operation of the ventilator with assistedcardiopulmonary resuscitation (CPR), it is, furthermore, advantageousthat the regulation does not respond to changes in the measuredventilation pressure (FIG. 2), which are caused by the cardiac massage(CM), during a pressure-controlled mode of ventilation, for example,CPAP, BiPAP, PC-PPS, PC-PS. The measured ventilation pressure isadvantageously filtered and/or delayed for this during the operation ofthe ventilator 1, 1′ (FIGS. 1, 1 b) with assisted cardiopulmonaryresuscitation (CPR) by means of suitable adaptation and delay elements33, 32 (FIG. 2). This filtering may be performed, for example, asamplitude filtering, mean value filtering or median filtering directlyon the measured value of the ventilation pressure (FIG. 2) or on valuesderived therefrom, as well as also in the further course of the signalprocessing, for example, before or on return into the control circuit.Time-based filtering is likewise possible with a monitoring time window.The monitoring time window may be, for example, such that changes in thevalues dP 35 (FIG. 2) of the ventilation pressure must last for acertain time before an adjustment (FIG. 2) of the ventilation pressureis performed by the control circuit. Oscillation buildup, transientoscillation or overshooting, or even a rise of the ventilation pressureas a response to the cardiac massage (CM) is prevented hereby.

In a coordinate system with an abscissa 740 and an ordinate 730, FIG. 6shows in the diagrams 506, 507, 508, 509 time curves of the ventilationof a patient during the operation of a ventilator with and withoutassisted cardiopulmonary resuscitation (CPR) (first and second modes ofoperation). The diagram shows a variation of the ventilation pressureduring the operation of the ventilator with assisted cardiopulmonaryresuscitation (CPR) (second mode of operation) compared to the operationof the ventilator without assisted cardiopulmonary resuscitation (CPR)(first mode of operation). In diagram 506, a curve drawn in broken lineshows a normal time curve of the ventilation pressure P_(N) 710 of amechanically ventilated patient as the alternation of inspiration andexpiration, as it is seen during the normal operation of a ventilatorwithout assisted cardiopulmonary resuscitation (CPR). The ventilationpressure P_(N) 710 is regulated by a control and regulation unit 7(FIGS. 1a, 1b ) during the normal operation of the ventilator 1, 1′(FIGS. 1a, 1b ) without assisted cardiopulmonary resuscitation (CPR)(first mode of operation) by a current value 610 (4) of the ventilationpressure, which is detected by a pressure sensor 13 (FIGS. 1a, 1b ),yielding a desired value for an actuation by a comparison with a firstpredetermined value 697, 16 (FIGS. 1a, 1b ) and by the control andregulation unit 7 (FIGS. 1a, 1b ) actuating an expiration valve 3 (FIGS.1a, 1b ) and an inspiration valve 2 (FIGS. 1a, 1b ) on the basis of thecomparison such that the current value 610 of the ventilation pressurecorresponds essentially to the first predetermined value 697, 16 (FIGS.1a, 1b ). In the sense of the present invention, the first predeterminedvalue is not only an individual value, to which the control andregulation unit 7 (FIGS. 1a, 1b ) regulates, but a chronologicalsequence of predetermined desired values, e.g., in the form of aventilation curve or of a course for controlling the ventilation. Thepressure of the gas exhaled by the patient at the patient port isdescribed by a first pressure time relationship (a first curve), and theflow control device is actuated during an inspiration phase such thatthe pressure of the gas supplied to the patient at the patient port isdescribed by a second pressure time relationship (a second curve),wherein the expiration phase and the inspiration phase follow each otherin a continuously alternating manner. Diagram 507 in FIG. 6 shows by acurve drawn in solid line a first alternative time curve 711 of theventilation pressure P_(A1) of a mechanically ventilated patient as thealternation of inspiration and expiration, as it is seen during theoperation of a ventilator with assisted cardiopulmonary resuscitation(CPR). The control and regulation unit is configured such that in thesecond mode of operation the flow control device is actuated during theexpiration phase such that the pressure of the gas exhaled by thepatient at the patient port is described by a third pressure timerelationship (a third curve), which pressure is increased compared tothe first pressure time relationship, at least during a section of theexpiration phase. In the second mode the flow control device is actuatedduring an inspiration phase such that the pressure of the gas suppliedto the patient at the patient port is described at least during asection of the inspiration phase by a fourth pressure time relationship(a fourth curve), which pressure is reduced compared to the secondpressure time relationship. The course of the normal ventilationpressure 710 according to the diagram 506 is also shown as a curve drawnin broken line in this diagram 507 to highlight the differences betweenthe first alternative time curve 711 and the normal time curve 710.

Just as it was described before for the normal operation of theventilator 1, 1′ (FIG. 1a, 1b ), the ventilation pressure P_(A) 711 isadjusted by the control and regulation unit 7 (FIGS. 1a, 1b ) to thefirst predetermined value 697, 16 (FIGS. 1a, 1b ) during the operationof the ventilator 1, 1′ (FIGS. 1a, 1b ) with assisted cardiopulmonaryresuscitation (CPR), with the peculiarity that the expiration valve 3(FIGS. 1a, 1b ) and the inspiration valve 2 (FIGS. 1a, 1b ) are actuatedby the control and regulation unit 7 (FIGS. 1a, 1b ) in a special mannersuch that a pressure P_(H) 722 increased by a second predetermined value698 is obtained at the start of the expiration phase of the first cycle760 of the ventilation, and that a pressure P_(L) 723 reduced by a thirdpredetermined value 690 is obtained at the start of the inspirationphase of the second cycle 770 of the ventilation. In addition, a diagram508 in FIG. 6 shows a curve drawn in solid line, which represents asecond alternative time curve 712 of the ventilation pressure P_(A2) ofa mechanically ventilated patient as the alternation of inspiration andexpiration, as it is seen during the operation of a ventilator withassisted cardiopulmonary resuscitation (CPR) (second mode of operation).The curve describing the normal ventilation pressure 710 according todiagram 506 is also shown as a curve drawn in broken line in thisdiagram 508 to highlight the differences between the second alternativetime curve 712 and the normal time curve 710. Just as it was describedbefore for the normal operation of the ventilator 1, 1′ (FIGS. 1a, 1b ),the ventilation pressure P_(A) 712 is adjusted by the control andregulation unit 7 (FIGS. 1a, 1b ) during the operation of the ventilator1, 1′ (FIGS. 1a, 1b ) with assisted cardiopulmonary resuscitation (CPR)(second mode of operation) to the first predetermined value 697, 16(FIGS. 1a, 1b ), with the peculiarity that the expiration valve 3 (FIGS.1a, 1b ) and the inspiration valve 2 (FIGS. 1a, 1b ) are actuated by thecontrol and regulation unit 7 (FIGS. 1a, 1b ) such that the first cycle760′ prolonged in time by a second predetermined time value 766 isobtained at the start of the expiration phase of the first cycle 760 ofthe ventilation, and that the second cycle 770′ shifted in time by athird predetermined time value 777 is obtained at the start of theinspiration phase of the second cycle 770 of the ventilation.Furthermore, a diagram 509 in the form of a curve drawn in broken linein FIG. 6 represents a third alternative time curve 713 of theventilation pressure P_(A3) of a mechanically ventilated patient, as itis obtained from a combination of the first alternative curve 711 fromdiagram 507 and the second alternative curve 712 from diagram 508 duringthe operation of a ventilator with assisted cardiopulmonaryresuscitation (CPR). The curve describing the normal ventilationpressure 710 according to diagram 506 is also shown as a curve drawn inbroken line in this diagram 509 to highlight the differences between thethird alternative time curve 713 and the normal time curve 710.

FIG. 7a shows in a schematic overview a medical system 1590 with aventilator 1, 1′ according to FIG. 1a or FIG. 1b and with an assistdevice 1500 for automatically performing a cardiac massage (CM). Theassist device 1500 is connected to the chest 1470 of a patient 47 bymeans of a compression element 1550. The assist device 1500 is connectedto the ventilator 1, 1′ via a sensor and data interface 30. The assistdevice 1500 sends a control signal 1560 to the ventilator 1, 1′ via thesensor and data interface 30 in order to bring the ventilator 1, 1′ intoa state of pause or to start or end an operation of the ventilator 1, 1′with assisted cardiopulmonary resuscitation (CPR) or to bring about achange in an alarm generation on the ventilator 1, 1′. The ventilator 1,1′ is able to bring the assist device 1500 into a state of pause bymeans of an additional control signal 1550.

FIG. 7b schematically shows a medical system 1690 with a ventilator 1,1′ according to FIG. 1a or FIG. 1b and with a voltagegenerator/defibrillator 1600 suitable for resuscitation. The voltagegenerator 1600 is connected to the chest 1470 of a patient 47 by meansof electrodes 1650. The voltage generator 1600 is connected to theventilator 1, 1′ via a sensor and data interface 30. The voltagegenerator 1600 sends a control signal 1660 to the ventilator 1, 1′ viathe sensor and data interface 30 in order to bring the ventilator 1, 1′into a state of pause or to bring about a change in an alarm generationon the ventilator 1, 1′.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:
 1. A ventilation system comprising: a gas supplydevice; a tube arrangement, wherein the tube arrangement has a patientport for connection to a patient in order to send gas from the gassupply device to the patient and in order to remove gas exhaled by thepatient; a flow control device for controlling the gas flow from the gassupply device to the patient port and for controlling the gas flow awayfrom the patient port; a sensor unit, which is arranged in the tubearrangement and is set up to detect parameters of the gas supplied tothe patient and exhaled by the patient; a control and regulation unitfor controlling the gas supply device and the flow control device, whichcontrol and regulation unit is connected to the gas supply device, tothe flow control device, and to the sensor unit, wherein: the controland regulation unit is configured to ensure that in a first mode ofventilation operation, the flow control device is actuated during anexpiration phase such that the pressure of the gas exhaled by thepatient at the patient port is described by a first pressure timerelationship with a decreasing expiration pressure, and the flow controldevice is actuated during an inspiration phase such that the pressure ofthe gas supplied to the patient at the patient port is described by asecond pressure time relationship with increasing inspiration pressure,wherein the expiration phase and the inspiration phase follow each otherin a continuously alternating manner; the control and regulation unit isconfigured to have a second mode of ventilation operation; the controland regulation unit is configured such that in the second mode ofventilation operation the flow control device is actuated during theexpiration phase such that the pressure of the gas exhaled by thepatient at the patient port is described by a third pressure timerelationship with decreasing expiration pressure, which is increasedcompared to the first pressure time relationship, at least during asection of the expiration phase, bringing about an increase in theinitial expiratory pressure level during said section of the expirationphase of the third pressure time relationship, relative to the firstpressure time relationship and hence an increase in an air-filled volumeof the patient's lungs; and the flow control device is actuated duringan inspiration phase such that the pressure of the gas supplied to thepatient at the patient port is described at least during a section ofthe inspiration phase by a fourth pressure time relationship, which isreduced compared to the second pressure time relationship, bringingabout a reduction of an initial inspiratory pressure level during saidsection of the inspiration phase of the fourth pressure timerelationship, relative to the second pressure time relationship, in thepatient's lungs; and a switchover device for switching over the controland regulation unit between the first and second modes of operation,wherein the switchover device is provided comprising a user input, withwhich a user can switch over the control and regulation unit between thefirst mode of ventilation operation and the second mode of ventilationoperation, wherein: the sensor unit has a sensor, which is configured todetermine the CO₂ content in the air exhaled by the patient during theexpiration phase; and the control and regulation unit is configured todetermine, from the CO₂ content in the air exhaled by the patient,whether a cardiopulmonary resuscitation is being performed on thepatient.
 2. A ventilation system in accordance with claim 1, wherein:the control and regulation unit is configured to actuate the flowcontrol device such that the expiration phase and the inspiration phaseeach have two consecutive partial phases, a first partial phase and asecond partial phase, in the second mode of ventilation operation; thepressure of the gas exhaled by the patient at the patient port isdescribed by the third pressure time relationship during the firstpartial phase of the expiration phase; the pressure of the gas exhaledby the patient at the patient port is described by a pressure timerelationship corresponding to the first pressure time relationshipduring the second partial phase of the expiration phase; the pressure ofthe gas supplied to the patient at the patient port is described by thefourth pressure time relationship during the first partial phase of theinspiration phase; and the pressure of the gas supplied to the patientat the patient port is described by a pressure time relationshipcorresponding to the second pressure time relationship during the secondpartial phase of the inspiration phase.
 3. A ventilation system inaccordance with claim 1, wherein the control and regulation unit isconfigured to actuate the flow control device during the expirationphase such that the third pressure time relationship of the pressure isobtained by increasing a desired pressure value.
 4. A ventilation systemin accordance with claim 1, wherein the control and regulation unit isconfigured to actuate the flow control device during the inspirationphase such that the fourth pressure time relationship of the pressure isobtained by reducing a desired pressure value.
 5. A ventilation systemin accordance with claim 1, wherein: the tube arrangement has abreathing gas outlet line, which leads away from the patient port andcan be opened and closed in relation to the patient port by anexpiration valve of the flow control device; the expiration valve isconnected to the control and regulation unit; and the control andregulation unit is configured to actuate the expiration valve during theexpiration phase such that it is opened with a time delay relative tothe start of the expiration phase.
 6. A ventilation system in accordancewith claim 1, wherein: the tube arrangement has a breathing gas supplyline, which leads from the gas supply unit to the patient port and canbe opened and closed in relation to the patient port by an inspirationvalve of the flow control device; the inspiration valve is connected tothe control and regulation unit; and the control and regulation unit isconfigured to actuate the inspiration valve during the inspiration suchthat it is opened with a time delay relative to the start of theinspiration phase.
 7. A ventilation system in accordance with claim 1,wherein the control and regulation unit is configured to comprise theswitchover device to determine, from the parameters detected by thesensor unit, whether a cardiopulmonary resuscitation is being performedon a patient connected to the patient port.
 8. A ventilation system inaccordance with claim 1, further comprising: a display unit, which isconnected to the control and regulation unit, wherein: the control andregulation unit is configured such that a first alarm message is sent tothe display device in the first mode of ventilation operation when aparameter detected by the sensor unit exceeds or falls below a thresholdvalue; and the control and regulation unit is configured not to send analarm message or to send a second alarm message different from the firstalarm message in the second mode of ventilation operation when theparameter detected by the sensor unit exceeds or falls below thethreshold value.
 9. A ventilation system in accordance with claim 8,wherein: the display unit has an acoustic signal device for generatingan acoustic alarm; the first alarm message comprises a first acousticalarm; and the second alarm message does not comprise an acoustic alarmor comprises a second acoustic alarm, which is different from the firstacoustic alarm and the second acoustic alarm has a volume that isreduced compared to that of the first acoustic alarm.
 10. A ventilationsystem in accordance with claim 1, further comprising a voltagegenerator for generating voltage pulses, which voltage generator isconnected to the control and regulation unit, wherein the voltagegenerator is provided with electrodes for connection to a patient.
 11. Aventilation system comprising: a gas supply device; a tube arrangement,wherein the tube arrangement has a patient port for connection to apatient in order to send gas from the gas supply device to the patientand in order to remove gas exhaled by the patient; a flow control devicefor controlling the gas flow from the gas supply device to the patientport and for controlling the gas flow away from the patient port; asensor unit, which is arranged in the tube arrangement and is set up todetect parameters of the gas supplied to the patient and exhaled by thepatient; a control and regulation unit for controlling the gas supplydevice and the flow control device, which control and regulation unit isconnected to the gas supply device, to the flow control device, and tothe sensor unit, wherein: the control and regulation unit is configuredto ensure that in a first mode of ventilation operation, the flowcontrol device is actuated during an expiration phase such that thepressure of the gas exhaled by the patient at the patient port isdescribed by a first pressure time relationship with a decreasingexpiration pressure, and the flow control device is actuated during aninspiration phase such that the pressure of the gas supplied to thepatient at the patient port is described by a second pressure timerelationship with increasing inspiration pressure, wherein theexpiration phase and the inspiration phase follow each other in acontinuously alternating manner; the control and regulation unit isconfigured to have a second mode of ventilation operation; the controland regulation unit is configured such that in the second mode ofventilation operation the flow control device is actuated during theexpiration phase such that the pressure of the gas exhaled by thepatient at the patient port is described by a third pressure timerelationship with decreasing expiration pressure, which is increasedcompared to the first pressure time relationship, at least during asection of the expiration phase, bringing about an increase in theinitial expiratory pressure level during said section of the expirationphase of the third pressure time relationship, relative to the firstpressure time relationship and hence an increase in an air-filled volumeof the patient's lungs; and the flow control device is actuated duringan inspiration phase such that the pressure of the gas supplied to thepatient at the patient port is described at least during a section ofthe inspiration phase by a fourth pressure time relationship, which isreduced compared to the second pressure time relationship, bringingabout a reduction of an initial inspiratory pressure level during saidsection of the inspiration phase of the fourth pressure timerelationship, relative to the second pressure time relationship, in thepatient's lungs; a switchover device for switching over the control andregulation unit between the first and second modes of operation, whereinthe switchover device is provided comprising a user input, with which auser can switch over the control and regulation unit between the firstmode of ventilation operation and the second mode of ventilationoperation; and a sensor for measuring the oxygen saturation in the blood(SPO,), which sensor can be connected to a patient, wherein: the controland regulation unit is configured to determine from the value of theoxygen saturation in the blood whether a cardiopulmonary resuscitationis being performed on the patient.
 12. A ventilation system inaccordance with claim 11, further comprising: a display unit, which isconnected to the control and regulation unit, wherein: the control andregulation unit is configured such that a first alarm message is sent tothe display device in the first mode of ventilation operation when aparameter detected by the sensor unit exceeds or falls below a thresholdvalue; and the control and regulation unit is configured not to send analarm message or to send a second alarm message different from the firstalarm message in the second mode of ventilation operation when theparameter detected by the sensor unit exceeds or falls below thethreshold value.
 13. A ventilation system in accordance with claim 12,wherein: the display unit has an acoustic signal device for generatingan acoustic alarm; the first alarm message comprises a first acousticalarm; and the second alarm message does not comprise an acoustic alarmor comprises a second acoustic alarm, which is different from the firstacoustic alarm and the second acoustic alarm has a volume that isreduced compared to that of the first acoustic alarm.
 14. A ventilationsystem in accordance with claim 11, wherein: the control and regulationunit is configured to actuate the flow control device such that theexpiration phase and the inspiration phase each have two consecutivepartial phases, a first partial phase and a second partial phase, in thesecond mode of ventilation operation; the pressure of the gas exhaled bythe patient at the patient port is described by the third pressure timerelationship during the first partial phase of the expiration phase; thepressure of the gas exhaled by the patient at the patient port isdescribed by a pressure time relationship corresponding to the firstpressure time relationship during the second partial phase of theexpiration phase; the pressure of the gas supplied to the patient at thepatient port is described by the fourth pressure time relationshipduring the first partial phase of the inspiration phase; and thepressure of the gas supplied to the patient at the patient port isdescribed by a pressure time relationship corresponding to the secondpressure time relationship during the second partial phase of theinspiration phase.
 15. A ventilation system in accordance with claim 11,wherein: the tube arrangement has a breathing gas outlet line, whichleads away from the patient port and can be opened and closed inrelation to the patient port by an expiration valve of the flow controldevice; the expiration valve is connected to the control and regulationunit; and the control and regulation unit is configured to actuate theexpiration valve during the expiration phase such that it is opened witha time delay relative to the start of the expiration phase; the tubearrangement has a breathing gas supply line, which leads from the gassupply unit to the patient port and can be opened and closed in relationto the patient port by an inspiration valve of the flow control device;the inspiration valve is connected to the control and regulation unit;and the control and regulation unit is configured to actuate theinspiration valve during the inspiration such that it is opened with atime delay relative to the start of the inspiration phase.
 16. Aventilation system comprising: a gas supply device; a tube arrangement,wherein the tube arrangement has a patient port for connection to apatient in order to send gas from the gas supply device to the patientand in order to remove gas exhaled by the patient; a flow control devicefor controlling the gas flow from the gas supply device to the patientport and for controlling the gas flow away from the patient port; asensor unit, which is arranged in the tube arrangement and is set up todetect parameters of the gas supplied to the patient and exhaled by thepatient; a control and regulation unit for controlling the gas supplydevice and the flow control device, which control and regulation unit isconnected to the gas supply device, to the flow control device, and tothe sensor unit, wherein: the control and regulation unit is configuredto ensure that in a first mode of ventilation operation, the flowcontrol device is actuated during an expiration phase such that thepressure of the gas exhaled by the patient at the patient port isdescribed by a first pressure time relationship with a decreasingexpiration pressure, and the flow control device is actuated during aninspiration phase such that the pressure of the gas supplied to thepatient at the patient port is described by a second pressure timerelationship with increasing inspiration pressure, wherein theexpiration phase and the inspiration phase follow each other in acontinuously alternating manner; the control and regulation unit isconfigured to have a second mode of ventilation operation; the controland regulation unit is configured such that in the second mode ofventilation operation the flow control device is actuated during theexpiration phase such that the pressure of the gas exhaled by thepatient at the patient port is described by a third pressure timerelationship with decreasing expiration pressure, which is increasedcompared to the first pressure time relationship, at least during asection of the expiration phase, bringing about an increase in theinitial expiratory pressure level during said section of the expirationphase of the third pressure time relationship, relative to the firstpressure time relationship and hence an increase in an air-filled volumeof the patient's lungs; and the flow control device is actuated duringan inspiration phase such that the pressure of the gas supplied to thepatient at the patient port is described at least during a section ofthe inspiration phase by a fourth pressure time relationship, which isreduced compared to the second pressure time relationship, bringingabout a reduction of an initial inspiratory pressure level during saidsection of the inspiration phase of the fourth pressure timerelationship, relative to the second pressure time relationship, in thepatient's lungs; and a switchover device for switching over the controland regulation unit between the first and second modes of operation,wherein the switchover device is provided comprising a user input, withwhich a user can switch over the control and regulation unit between thefirst mode of ventilation operation and the second mode of ventilationoperation, wherein the sensor unit has a sensor, which is configured todetermine the oxygen content in the air exhaled by the patient duringthe expiration phase; and the control and regulation unit is configuredto determine from the oxygen content in the air exhaled by the patientwhether a cardiopulmonary resuscitation is being performed on thepatient.
 17. A ventilation system in accordance with claim 16, furthercomprising: a display unit, which is connected to the control andregulation unit, wherein: the control and regulation unit is configuredsuch that a first alarm message is sent to the display device in thefirst mode of ventilation operation when a parameter detected by thesensor unit exceeds or falls below a threshold value; and the controland regulation unit is configured not to send an alarm message or tosend a second alarm message different from the first alarm message inthe second mode of ventilation operation when the parameter detected bythe sensor unit exceeds or falls below the threshold value.
 18. Aventilation system in accordance with claim 17, wherein: the displayunit has an acoustic signal device for generating an acoustic alarm; thefirst alarm message comprises a first acoustic alarm; and the secondalarm message does not comprise an acoustic alarm or comprises a secondacoustic alarm, which is different from the first acoustic alarm and thesecond acoustic alarm has a volume that is reduced compared to that ofthe first acoustic alarm.
 19. A ventilation system in accordance withclaim 16, wherein: the control and regulation unit is configured toactuate the flow control device such that the expiration phase and theinspiration phase each have two consecutive partial phases, a firstpartial phase and a second partial phase, in the second mode ofventilation operation; the pressure of the gas exhaled by the patient atthe patient port is described by the third pressure time relationshipduring the first partial phase of the expiration phase; the pressure ofthe gas exhaled by the patient at the patient port is described by apressure time relationship corresponding to the first pressure timerelationship during the second partial phase of the expiration phase;the pressure of the gas supplied to the patient at the patient port isdescribed by the fourth pressure time relationship during the firstpartial phase of the inspiration phase; and the pressure of the gassupplied to the patient at the patient port is described by a pressuretime relationship corresponding to the second pressure time relationshipduring the second partial phase of the inspiration phase.
 20. Aventilation system in accordance with claim 16, wherein: the tubearrangement has a breathing gas outlet line, which leads away from thepatient port and can be opened and closed in relation to the patientport by an expiration valve of the flow control device; the expirationvalve is connected to the control and regulation unit; and the controland regulation unit is configured to actuate the expiration valve duringthe expiration phase such that it is opened with a time delay relativeto the start of the expiration phase; the tube arrangement has abreathing gas supply line, which leads from the gas supply unit to thepatient port and can be opened and closed in relation to the patientport by an inspiration valve of the flow control device; the inspirationvalve is connected to the control and regulation unit; and the controland regulation unit is configured to actuate the inspiration valveduring the inspiration such that it is opened with a time delay relativeto the start of the inspiration phase.